Marcus found out about Tony's suspicions three days later, entirely by accident.
He'd been doing his usual surveillance routine—floating around the city as Winged Kuriboh, checking in on various locations, making sure no new threats were emerging. It was peaceful work, almost meditative. The city sprawled below him like a living organism, millions of lives intersecting and diverging, each one a story he'd never know.
And then he'd decided to swing by Avengers Tower. Just to check in. Just to see how his "lore dump" had been received.
What he heard made his tiny Kuriboh heart stop.
"—signatures are too consistent. I'm telling you, Bruce, this is one person. One incredibly talented shapeshifter who's running circles around us."
Tony's voice, coming through an open window on the lab floor. Marcus floated closer, pressing his fluffy body against the glass.
"The dimensional energy readings support the multiple beings theory," Bruce's voice responded, sounding uncertain. "The variations in manifestation type, the different power signatures—"
"All consistent with a single consciousness adapting to different forms. JARVIS ran the numbers. The emotional patterns, the speech rhythms, the underlying humor—it's all the same person, Bruce. We're being played."
Marcus felt his stomach drop.
No. No no no. This wasn't supposed to happen. He'd been so CAREFUL. He'd crafted distinct personalities, different speech patterns, varied approaches for each monster form. How had Tony figured it out?
"Even if you're right," Bruce said slowly, "does it matter? They're still helping. They stopped HYDRA. They warned us about Thanos. Whether it's one being or many, the actions are beneficial."
"It matters because they're LYING to us. Deliberately, elaborately, consistently lying. And when someone goes to that much trouble to deceive you, there's always a reason. I want to know what it is."
Marcus floated away from the window, his mind racing.
This was bad. This was really, really bad.
If Tony convinced the rest of the team that the Duel Spirits were actually one person, everything would change. They'd start looking for his human form. They'd analyze patterns, track movements, eventually figure out that there was a guy in Hell's Kitchen who kept disappearing right before monster sightings.
His whole carefully constructed web of misdirection would collapse.
He needed to fix this.
He needed to fix this NOW.
But how? He couldn't just show up and say "no really, we're definitely multiple beings, please believe me." That would only make Tony MORE suspicious. He needed something bigger. Something that would make the "single shapeshifter" theory seem ridiculous.
He needed to do something that no single being could possibly do.
Marcus floated to a nearby rooftop and transformed back to human form, pacing frantically as he thought.
"Okay. Okay. What would prove we're multiple entities? What would be impossible for one person to fake?"
The answer came to him slowly, terrifyingly, wonderfully.
Exodia.
Exodia the Forbidden One.
In the game, Exodia was unique—it wasn't one monster but FIVE, five separate pieces that had to be assembled to form the complete being. The Left Arm, the Right Arm, the Left Leg, the Right Leg, and the Head. Each piece was its own card, its own entity, and only when all five were brought together did Exodia's true power manifest.
In the LORE, Exodia was something even more significant. It was an ancient demon of such immense power that the gods themselves had been forced to seal it away, splitting its body into five pieces and scattering them across the world. The pieces retained their own consciousness, their own will, but they longed to be reunited—and when they were, nothing could stand against them.
If Marcus could manifest Exodia as five SEPARATE beings—five distinct entities that then combined into one—it would prove beyond any doubt that the Duel Spirits were not a single shapeshifter. Because no shapeshifter could be in five places at once.
It was insane.
It was brilliant.
It was the most ridiculous thing he'd ever attempted.
"I'm going to summon Exodia," Marcus whispered to himself. "I'm going to summon the Forbidden One to win an argument with Tony Stark. This is my life now."
He started planning.
Two Days Later
Marcus's Apartment
The preparation had been intense.
Marcus had spent every waking moment practicing. He'd discovered that while he could only maintain ONE monster form at a time, he could... echo. Project. Create temporary manifestations that lasted for a few seconds before dissolving.
It wasn't true multiplication. But with precise timing and careful staging, he could create the ILLUSION of multiple beings existing simultaneously.
The trick would be the combination sequence. He needed to manifest all five pieces of Exodia in different locations, then have them "travel" toward a central point and merge into the complete form. If he could pull it off, the whole process would be visible on cameras across the city—irrefutable evidence of five separate entities becoming one.
It would also be the most draining thing he'd ever done. The Numeron Dragon transformation had knocked him out for days. This might actually kill him.
"Worth it," Marcus muttered, reviewing his plans. "Totally worth it to prove a point to a billionaire."
He'd chosen his locations carefully. Five spots across Manhattan, each visible to major traffic cameras and news helicopters. The convergence point would be Central Park—open space, maximum visibility, minimum chance of property damage.
He'd tipped off the media. Not directly, but through a series of carefully placed hints that "something major" was going to happen at exactly 3:00 PM today. The news networks would have helicopters in the air. The whole world would be watching.
And Tony Stark, specifically, would be watching. Marcus had made sure JARVIS would flag the event as "Duel Spirit activity, high priority."
"Okay," Marcus said, taking a deep breath. "Let's do this."
He transformed into Winged Kuriboh and flew toward his first position.
Manhattan
2:57 PM
The city was going about its normal business, completely unaware that reality was about to get very weird.
In Times Square, a street performer was doing card tricks for tourists.
On Wall Street, traders were shouting at screens and each other.
Near the United Nations building, diplomats were having a very boring meeting about trade regulations.
At Columbus Circle, a hot dog vendor was arguing with a customer about mustard.
And in Bryant Park, a chess hustler was about to win his fifteenth game of the day.
At exactly 2:58 PM, all five locations experienced simultaneous reality distortions.
Times Square
2:58 PM
The street performer was in the middle of his finale—the classic "is this your card" reveal—when the sky above Times Square turned gold.
Not metaphorically. The actual sky, the actual air, turned a shimmering golden color, as if someone had placed a filter over reality itself.
And then IT appeared.
A massive arm, easily thirty feet long, covered in ancient armor and golden bindings. It materialized from nothing, hanging in the air above the famous billboards, fingers flexing slowly as if testing its range of motion.
The arm had no body. It was just... an arm. A left arm, specifically, with intricate chains wrapped around its wrist and elbow.
"WHAT THE HELL IS THAT?!" someone screamed.
The arm turned—somehow, despite having no eyes—toward the crowd below.
"I AM THE LEFT ARM OF THE FORBIDDEN ONE," a voice boomed from nowhere and everywhere. "I HAVE BEEN SUMMONED. THE ASSEMBLY BEGINS."
And then the arm began to move, floating through the air toward the south, leaving a trail of golden energy in its wake.
The street performer fainted.
His cards scattered in the wind.
Nobody noticed.
Wall Street
2:58 PM
The traders had seen a lot of things during their careers. Market crashes. Flash crashes. That one time a guy had brought a live chicken onto the trading floor as a "good luck charm."
They had not seen a giant floating RIGHT arm materialize above the New York Stock Exchange.
"I AM THE RIGHT ARM OF THE FORBIDDEN ONE," the arm announced, its voice causing the building's windows to rattle. "THE ASSEMBLY BEGINS. THE FORBIDDEN ONE SHALL BE WHOLE ONCE MORE."
A trader named Doug dropped his coffee.
"Is this... is this affecting the markets?" he asked weakly.
The arm flew away toward the north, leaving chaos in its wake.
The markets, for the record, did experience a brief dip. But they recovered.
Doug never did.
United Nations
2:58 PM
The meeting about trade regulations was interrupted by what the official report would later describe as "an unexplained manifestation of unknown origin."
What actually happened was that a giant LEFT LEG appeared outside the window, its armored surface reflecting the afternoon sun.
"I AM THE LEFT LEG OF THE FORBIDDEN ONE," it announced, causing the translator systems to short-circuit in confusion. "THE ASSEMBLY BEGINS."
The Russian delegate turned to the American delegate.
"Is this yours?"
"Why would this be OURS?"
"You have Avengers!"
"We don't have giant floating LEGS!"
The leg flew away toward the west, and the meeting was adjourned indefinitely.
Columbus Circle
2:58 PM
The hot dog vendor and his customer stopped arguing about mustard when the RIGHT LEG appeared.
It was, objectively speaking, an impressive leg. Muscular, armored, radiating power that made the air taste like static electricity.
"I AM THE RIGHT LEG OF THE FORBIDDEN ONE," it declared. "THE CHAINS THAT BOUND ME ARE BREAKING. THE ASSEMBLY BEGINS."
"Well," the customer said faintly, "I guess mustard doesn't matter that much after all."
The vendor nodded in agreement.
The leg flew away toward the east.
They both decided to take the rest of the day off.
Bryant Park
2:58 PM
The chess hustler was about to claim victory when his opponent suddenly looked up at the sky and screamed.
The HEAD of Exodia was descending.
It was, without question, the most terrifying thing anyone in the park had ever seen. A massive face, ancient and stern, with eyes that glowed like dying stars. Chains wrapped around its neck and jaw, remnants of bindings that had held it imprisoned for millennia.
"I AM THE HEAD OF THE FORBIDDEN ONE," it spoke, and its voice was different from the limbs—deeper, more commanding, the voice of something that had been worshipped and feared in equal measure. "MY BRETHREN GATHER. THE SEALS ARE BREAKING. THE FORBIDDEN ONE... SHALL RISE."
The chess hustler looked at his opponent.
"I think we can call this game a draw."
The head flew away toward the south, joining the convergence that everyone in Manhattan was now watching.
Avengers Tower
2:59 PM
"JARVIS, what am I looking at?"
Tony stood in front of a wall of screens, each one showing a different news feed. Every channel was covering the same story: five separate entities, appearing simultaneously across Manhattan, all claiming to be pieces of something called "the Forbidden One."
"The manifestations match descriptions from the Yu-Gi-Oh database, sir. Specifically, they appear to be the five pieces of 'Exodia the Forbidden One,' a legendary monster in the game's lore."
"Five pieces. Five separate pieces. Appearing at the same time in five different locations."
"Correct, sir."
Tony's eye twitched.
"That's... that's not possible for a single shapeshifter."
"It would appear not, sir. Unless the entity possesses the ability to be in multiple places simultaneously, this would confirm the 'multiple distinct beings' theory."
Steve, Natasha, Thor, Clint, and Bruce had all gathered behind Tony, watching the screens in various states of shock.
"The limbs are converging," Bruce observed. "They're all heading toward... Central Park?"
The screens showed exactly that. Five golden trails of energy, cutting across the Manhattan sky, all aimed at the Great Lawn in Central Park.
"We need to be there," Steve said immediately.
"We need to be CAREFUL," Natasha corrected. "We don't know what happens when those pieces combine."
"According to the game's lore," Clint said, reading from his phone, "when all five pieces of Exodia are assembled, it results in an 'instant win.' The complete Exodia has unlimited power."
"Unlimited," Tony repeated flatly.
"That's what it says."
"Great. So we're about to witness the assembly of an unlimited power cosmic entity. In Central Park. During rush hour."
"SIR," JARVIS interrupted, "THE PIECES ARE ARRIVING AT THE CONVERGENCE POINT."
Everyone turned back to the screens.
Central Park
3:00 PM
The five pieces of Exodia arrived simultaneously, descending from different directions to hover above the Great Lawn. The park had been evacuated—police had responded quickly to the "multiple giant body parts flying across Manhattan" situation—and now only news helicopters and brave/foolish bystanders remained to witness what came next.
The pieces began to circle each other, slowly at first, then faster and faster. Golden energy crackled between them, arcs of power connecting arm to leg, leg to head, forming a web of light that grew brighter with each passing moment.
And then they spoke.
"I AM THE LEFT ARM," said the left arm.
"I AM THE RIGHT ARM," said the right arm.
"I AM THE LEFT LEG," said the left leg.
"I AM THE RIGHT LEG," said the right leg.
"I AM THE HEAD," said the head.
"WE ARE FRAGMENTS," they chorused, their voices harmonizing into something greater than any individual part. "SEPARATED BY GODS WHO FEARED OUR POWER. SCATTERED ACROSS DIMENSIONS. BOUND BY CHAINS OF COSMIC FORCE."
The circling accelerated.
"BUT THE CHAINS ARE BREAKING. THE SEALS ARE WEAKENING. THE BARRIERS BETWEEN WORLDS HAVE CRACKED."
The light grew almost unbearable.
"AND NOW..."
The five pieces collided, merged, became ONE.
"...THE FORBIDDEN ONE IS WHOLE ONCE MORE."
Marcus, at the center of the transformation, was experiencing something beyond words.
He'd done it. He'd actually done it. The five-piece manifestation had worked, and now he was fully, completely, utterly Exodia the Forbidden One.
And it was OVERWHELMING.
The power. The POWER. It was nothing like his other transformations. Numeron Dragon had been intense, but it was focused, directed, a cosmic energy with purpose. Exodia was... raw. Primal. The kind of power that existed before concepts like "limits" had been invented.
He could feel the Earth beneath him. Not just the ground—the entire PLANET, every atom, every molecule, every living thing. He could feel the boundaries of this reality and the infinite dimensions beyond. He could feel the threads of causality stretching into past and future.
He could, if he wanted, END things. Not destroy them—END them. Make them never have been.
It was terrifying.
It was INCREDIBLE.
And he needed to focus, because he had a performance to give.
Central Park
3:02 PM
The complete Exodia stood in the center of the Great Lawn, a titan of gold and ancient power. Its body was humanoid but massive—easily a hundred feet tall, covered in ornate armor and mystical chains that now hung loose, broken, symbols of imprisonment that no longer held.
Its eyes surveyed the city around it with something that might have been curiosity.
"SO," it said, and its voice shook buildings across Manhattan, "THIS IS THE WORLD THAT HAS DRAWN SO MANY OF MY BRETHREN. THIS IS THE REALM THAT FACES SUCH THREATS THAT THE DUEL SPIRITS HAVE CHOSEN TO INTERVENE."
The news helicopters circled at a respectful distance, cameras capturing every moment.
"I AM EXODIA. THE FORBIDDEN ONE. THE SEALED DEMON. THE POWER THAT GODS THEMSELVES COULD NOT DESTROY."
A pause.
"I AM ALSO," and here Marcus let a hint of humor enter the cosmic voice, "VERY HAPPY TO BE IN ONE PIECE AGAIN. YOU HAVE NO IDEA HOW UNCOMFORTABLE IT IS TO BE SCATTERED ACROSS FIVE DIMENSIONS."
Avengers Tower
"Did..." Tony stared at the screen. "Did the unlimited power demon just make a JOKE?"
"It appears so, sir," JARVIS confirmed.
"It has the same sense of humor as the others," Natasha observed. "The same underlying personality."
"Because they're from the same dimension," Bruce said slowly. "Same origin, same cultural context, same... sense of humor. It doesn't mean they're the same being."
Tony's carefully constructed theory was falling apart, and he could feel it.
Five pieces. Five SEPARATE pieces, appearing simultaneously across the city, each one visible on dozens of cameras. There was no way a single shapeshifter could have done that. There was no WAY.
Unless...
"JARVIS, analyze the energy signatures from each piece before they combined. Are they identical or distinct?"
"Analyzing... The signatures are similar but not identical, sir. Each piece has unique variations consistent with being a separate entity that shares a common dimensional origin."
"Damn it."
"If it helps, sir, the 'single shapeshifter' theory is not entirely ruled out. Theoretically, an entity with sufficient power could project itself into multiple locations simultaneously—"
"But that would require MORE power than just being multiple beings," Bruce pointed out. "Occam's Razor says the simpler explanation is probably correct."
Tony slumped in his chair.
He'd been so SURE.
Central Park
3:05 PM
Exodia had been standing in contemplative silence for a few minutes, enjoying the sensation of being complete while Marcus figured out how to proceed with his plan.
The Avengers would be watching. Tony specifically would be watching. And Marcus needed to deliver a message that would put Tony's suspicions to rest once and for all.
Time for the performance of a lifetime.
"I SENSE..." Exodia turned its massive head toward the north, toward Avengers Tower. "...THOSE WHO QUESTION. THOSE WHO DOUBT. THOSE WHO HAVE BEEN... THEORIZING."
The helicopters swung to capture whatever the demon was looking at.
"ANTHONY STARK," Exodia said, and even from miles away, somehow the words were perfectly audible in the Tower's conference room. "I WOULD SPEAK WITH YOU."
Avengers Tower
Everyone turned to look at Tony.
"Why is the unlimited power demon calling me out specifically?" Tony asked, sounding slightly strangled.
"Perhaps because of your... investigation?" Bruce suggested delicately.
"How would it know about that?"
"It's unlimited," Clint pointed out. "Maybe it just... knows stuff."
"I KNOW YOU HAVE BEEN INVESTIGATING US," Exodia's voice continued, somehow carrying through the Tower's walls. "I KNOW YOU BELIEVE WE ARE A DECEPTION. A SINGLE ENTITY WEARING MANY MASKS."
Tony's face went through several complex expressions.
"I WISH TO... CLARIFY THE SITUATION. WILL YOU MEET WITH ME? I GIVE MY WORD THAT NO HARM WILL COME TO YOU OR YOUR ALLIES."
"Tony, you can't seriously be considering—" Natasha started.
"JARVIS, is there any way that thing could hurt us if it wanted to?"
"Based on the power readings I'm detecting, sir, it could likely destroy the Eastern seaboard with minimal effort. If it wished us harm, we would already be harmed."
"Great. So refusing the meeting would just be pointless AND rude." Tony stood up. "I'm going."
"We're ALL going," Steve corrected.
"The more the merrier, I guess."
Central Park
3:15 PM
The Avengers arrived in style—Iron Man carrying Captain America, Thor flying under his own power, a Quinjet carrying Natasha, Clint, and Bruce. They landed at the edge of the Great Lawn, maintaining a respectful distance from the towering figure of Exodia.
Up close, the demon was even more impressive. Every detail of its armor seemed to contain smaller details, patterns within patterns, as if its very surface was fractal in nature. The chains that hung from its limbs clinked gently in a nonexistent wind.
"AVENGERS," Exodia said, lowering its head to look at them more directly. "THANK YOU FOR COMING."
"Did we have a choice?" Tony asked, his faceplate retracting so he could speak face-to-face. Well, face-to-giant-face.
"THERE IS ALWAYS A CHOICE. YOU CHOSE COURAGE OVER CAUTION. I RESPECT THAT."
"You said you wanted to clarify something. About us thinking you're all one person."
"YES." Exodia gestured with one massive arm, encompassing itself and the city beyond. "YOU HAVE OBSERVED THE DUEL SPIRITS WHO HAVE COME TO THIS DIMENSION. YOU HAVE ANALYZED THEIR ENERGY SIGNATURES, THEIR SPEECH PATTERNS, THEIR BEHAVIOR. AND YOU HAVE CONCLUDED THAT WE ARE A DECEPTION."
Tony's jaw tightened. "Your friends were pretty convincing. But there were... inconsistencies. Things that didn't add up."
"AND WHAT CONCLUSION DID YOU DRAW FROM THESE INCONSISTENCIES?"
"That you're all the same being. One shapeshifter pretending to be multiple entities."
Exodia was silent for a moment.
Then, impossibly, it laughed.
The sound was like thunder mixed with earthquakes, rolling across the park and probably registering on seismographs across the state. But it was also, unmistakably, genuine amusement.
"ANTHONY STARK," Exodia said, still chuckling. "YOU ARE BRILLIANT. TRULY, GENUINELY BRILLIANT. TO HAVE PIECED TOGETHER AS MUCH AS YOU DID, WITH THE LIMITED INFORMATION AVAILABLE TO YOU... IT IS IMPRESSIVE."
"But I'm wrong?"
"YOU ARE WRONG." Exodia gestured upward, and the sky above them shimmered, displaying images like a cosmic projector. "OBSERVE."
The images showed the Duel Spirit realm—the same visions that Dark Magician had shown during the lore dump, but more detailed, more vivid. Thousands of monsters moving through impossible landscapes, living their lives, interacting with each other.
"WE ARE MANY," Exodia explained. "TRULY MANY. DISTINCT BEINGS WITH DISTINCT WILLS, DISTINCT PERSONALITIES, DISTINCT DESIRES. WE SHARE A COMMON ORIGIN, A COMMON SOURCE OF POWER, A COMMON PURPOSE IN COMING TO THIS DIMENSION. BUT WE ARE NOT ONE."
"Then why the similarities?" Tony pressed. "The same humor, the same speech patterns, the same underlying vibe?"
"BECAUSE WE ARE FAMILY."
The word hung in the air, simple and profound.
"NOT IN THE BIOLOGICAL SENSE—WE DO NOT REPRODUCE AS YOU DO. BUT WE HAVE EXISTED TOGETHER FOR EONS. WE HAVE SHARED EXPERIENCES, SHARED MEMORIES, SHARED GROWTH. WE HAVE INFLUENCED EACH OTHER IN COUNTLESS WAYS."
The images shifted, showing different monsters interacting over vast stretches of time. Training together. Fighting together. Playing together.
"WHEN BEINGS SPEND LONG ENOUGH IN EACH OTHER'S COMPANY, THEY BEGIN TO REFLECT EACH OTHER. SPEECH PATTERNS CONVERGE. SENSES OF HUMOR ALIGN. UNDERLYING PHILOSOPHIES MERGE."
Marcus was improvising wildly here, but it SOUNDED good. It sounded plausible. It was the kind of explanation that a brilliant mind like Tony's would accept—not because it was necessarily true, but because it was INTERNALLY CONSISTENT.
"YOU DETECTED SIMILARITIES BECAUSE SIMILARITIES EXIST. BUT SIMILARITY IS NOT IDENTITY. MY BRETHREN AND I ARE DISTINCT. AS PROOF..."
Exodia raised one hand, and five points of light separated from its body—reforming, briefly, into the five pieces that had assembled earlier.
"WE CAN BE APART," the pieces chorused. "WE CHOOSE TO BE TOGETHER. THERE IS A DIFFERENCE."
The pieces recombined, and Exodia was whole once more.
"DOES THIS SATISFY YOUR CURIOSITY, ANTHONY STARK?"
Tony was quiet for a long moment, his genius mind processing everything he'd seen and heard.
Then he sighed.
"I was so sure," he muttered. "The data supported my theory perfectly."
"THE DATA SUPPORTED MULTIPLE THEORIES. YOU CHOSE THE ONE THAT APPEALED TO YOUR INSTINCTS. IT WAS A REASONABLE CHOICE—DECEPTION IS COMMON IN YOUR EXPERIENCE. BUT IT WAS NOT CORRECT."
"No, apparently not." Tony shook his head. "Fine. You're multiple beings. I accept that. But I still have questions."
"ASK."
"Why the secrecy? Why the elaborate presentations and dramatic appearances? If you're here to help, why not just... say so? Directly? Without all the theater?"
This was a question Marcus had been prepared for.
"BECAUSE YOUR WORLD IS NOT READY."
Exodia's voice grew more serious, the humor fading.
"IF WE APPEARED AS WE TRULY ARE—OPENLY, OBVIOUSLY, AS BEINGS FROM ANOTHER DIMENSION HERE TO PROTECT YOU—IT WOULD CAUSE CHAOS. GOVERNMENTS WOULD PANIC. RELIGIONS WOULD FRACTURE. THE SOCIAL ORDER YOU DEPEND ON WOULD BE THROWN INTO TURMOIL."
The images above shifted again, showing scenes of chaos and fear. Riots. Wars. Civilization crumbling.
"WE HAVE SEEN IT HAPPEN IN OTHER DIMENSIONS. THE TRUTH, DELIVERED TOO QUICKLY, CAN BE AS DESTRUCTIVE AS ANY ENEMY. SO WE APPROACH CAREFULLY. WE BUILD TRUST. WE ALLOW YOUR WORLD TO ADJUST GRADUALLY TO OUR PRESENCE."
"And the different forms? The variety?"
"DIFFERENT SITUATIONS REQUIRE DIFFERENT APPROACHES. A COSMIC DRAGON IS APPROPRIATE FOR WARNING OF COSMIC THREATS. A SMALL FLUFFY CREATURE IS APPROPRIATE FOR STOPPING STREET CRIME WITHOUT CAUSING TERROR. WE ADAPT TO CIRCUMSTANCES."
Steve stepped forward, apparently deciding to join the conversation.
"You said you're here to protect us. Protect us from what, specifically?"
"MANY THINGS." Exodia turned its attention to the Captain. "THANOS, AS THE NUMERON DRAGON WARNED. INTERNAL THREATS LIKE HYDRA. SUPERNATURAL DANGERS THAT YOUR SCIENCE CANNOT ADDRESS. AND..."
A pause.
"...THREATS FROM OUR OWN REALM. NOT ALL DUEL SPIRITS ARE BENEVOLENT. SOME WOULD SEEK TO CONQUER YOUR DIMENSION, ENSLAVE YOUR PEOPLE, TURN YOUR WORLD INTO A REFLECTION OF THEIR DARKEST DESIRES."
"So you're not just here to help us," Natasha said, her voice sharp. "You're here to police your own kind."
"IN PART, YES. IF MALEVOLENT SPIRITS CROSS INTO YOUR DIMENSION, IT IS OUR RESPONSIBILITY TO STOP THEM. WE CANNOT ALLOW OUR REALM'S CONFLICTS TO DESTROY YOUR WORLD."
"That's... surprisingly responsible," Bruce admitted.
"WE HAVE EXISTED FOR A VERY LONG TIME, DR. BANNER. WE HAVE LEARNED THE CONSEQUENCES OF IRRESPONSIBILITY."
Thor, who had been unusually quiet, finally spoke up.
"Exodia. Forbidden One. I have a question that has been weighing on my mind."
"ASK, THOR ODINSON."
"When the time comes—when Thanos arrives and the battle for all existence begins—will you and your brethren stand with us? Will you fight alongside the Avengers as allies in the true sense?"
Exodia was silent for a long moment.
Then, slowly, the towering demon knelt—KNELT—bringing its massive head down to Thor's level, meeting his eyes directly.
"THOR," it said, and the voice was gentler now, more personal. "WHEN THANOS COMES, WHEN THE MAD TITAN REACHES FOR THE INFINITY STONES, WHEN HALF OF ALL LIFE HANGS IN THE BALANCE... WE WILL BE THERE."
Its eyes glowed brighter.
"NOT JUST THE FEW WHO HAVE CROSSED INTO YOUR DIMENSION. ALL OF US. THE ENTIRE HOST OF DUEL SPIRITS, EVERY DRAGON AND SPELLCASTER AND WARRIOR AND MACHINE, EVERY BEING WHO CALLS OUR REALM HOME. WE WILL COME."
Thor's expression shifted into something fierce and joyful.
"Then we shall have a GRAND battle! The stuff of legends! Songs will be sung of it for ten thousand years!"
"I LOOK FORWARD TO IT," Exodia agreed, and Marcus was surprised to find that he meant it. The idea of actually fighting Thanos with an army of Duel Monsters was... kind of awesome, actually.
"BUT THAT DAY IS NOT TODAY." Exodia rose back to its full height. "TODAY IS FOR UNDERSTANDING. FOR BUILDING TRUST. FOR LAYING THE GROUNDWORK FOR THE ALLIANCE TO COME."
"And for completely destroying my theory about you being one person," Tony added, sounding almost amused now.
"THAT WAS ALSO A CONSIDERATION," Exodia admitted. "YOUR SUSPICION, WHILE INCORRECT, WAS CLOSE ENOUGH TO THE TRUTH OF OUR CONNECTION THAT IT NEEDED TO BE ADDRESSED. WE CANNOT HAVE EARTH'S GREATEST ANALYTICAL MIND DISTRACTED BY THE WRONG PUZZLE."
"Wait." Tony's eyes narrowed. "Close enough to the truth? What does that mean?"
Marcus internally cursed. He'd said too much.
"WE ARE CONNECTED," Exodia said, recovering quickly. "MORE CONNECTED THAN SEPARATE BEINGS USUALLY ARE. OUR THOUGHTS CAN TOUCH. OUR EXPERIENCES CAN BE SHARED. IN SOME WAYS, WE ARE MORE LIKE... A NETWORK THAN A COLLECTION OF INDIVIDUALS."
"A hive mind?"
"NO. A HIVE MIND IMPLIES A SINGLE CONTROLLING CONSCIOUSNESS. WE ARE MORE LIKE... A FAMILY THAT NEVER STOPS TALKING TO EACH OTHER. EACH VOICE IS DISTINCT, BUT ALL VOICES ARE HEARD."
Tony considered this.
"That would explain the consistency," he admitted. "A shared information network would create similar behavioral patterns without requiring a single entity."
"PRECISELY. YOUR ANALYSIS WAS NOT WRONG IN ITS OBSERVATIONS—ONLY IN ITS CONCLUSIONS."
"I still think you're hiding something," Tony said, but his tone was more curious than accusatory now. "There's something about this whole situation that doesn't quite add up. But I can't figure out what it is."
"PERHAPS THAT IS BECAUSE SOME TRUTHS ARE NOT MEANT TO BE FIGURED OUT. SOME MYSTERIES ARE BETTER LEFT MYSTERIOUS."
"That's not ominous at all."
"I NEVER CLAIMED NOT TO BE OMINOUS. I AM A FORBIDDEN DEMON COMPOSED OF FIVE SEPARATE PIECES. OMINOUS IS MY DEFAULT STATE."
Tony actually laughed at that—a genuine, surprised laugh.
"Okay. Fine. You've convinced me. You're multiple beings. You're here to help. You're annoyingly cryptic but apparently trustworthy." He extended his hand toward the towering figure. "Alliance?"
Exodia looked at the tiny human hand being offered.
Then, very carefully, it extended one massive finger and touched it to Tony's palm.
"ALLIANCE."
Later
After Exodia Had Departed
The Avengers reconvened in their conference room, processing what had just happened.
"So," Steve said slowly. "We just made an alliance with a demon. A 'Forbidden' demon. That's composed of five pieces."
"To be fair, it seems like a nice demon," Clint offered.
"It said it has 'unlimited power' and it was sealed away by gods. That doesn't sound 'nice.'"
"It also made jokes and promised to help us fight Thanos. That sounds pretty nice to me."
"The point," Tony interjected, "is that we now have confirmation—multiple times over—that we're dealing with a genuine interdimensional coalition of spirits. Not a single shapeshifter. Not a deception. Actual, multiple, distinct beings."
"You seem disappointed," Natasha observed.
"I'm not disappointed. I'm... frustrated. I was so SURE I had figured it out. The data was so clean. But apparently I was just seeing patterns that weren't there."
"That happens sometimes," Bruce said sympathetically. "Even the best minds can be led astray by confirmation bias."
"Thanks, Bruce. That's very comforting."
"What matters," Steve cut in, "is that we have allies. Powerful allies who are already committed to helping us prepare for future threats. That's what we should be focusing on."
"Agreed," Thor said. "The Duel Spirits are noble warriors! We should celebrate our new alliance! Feast! Song! Perhaps some friendly combat to test our mettle!"
"Maybe save the friendly combat for later," Natasha suggested. "We still don't know the full extent of their capabilities. I'd rather not find out by getting punched by a giant demon."
"A fair point."
Tony was quiet, staring at nothing in particular.
"JARVIS," he said finally. "Close the 'single shapeshifter' investigation file. Archive everything—we might need it later—but mark it as 'theory disproven.'"
"Done, sir. Shall I update the Duel Spirit database with the new information from today's encounter?"
"Yeah. And add a note: 'these guys are weird but apparently trustworthy. Maintain cautious optimism.'"
"Noted, sir."
Tony leaned back in his chair, staring at the ceiling.
Somewhere out there, a coalition of interdimensional card game spirits was watching over the world. They'd stopped HYDRA, warned of Thanos, and now pledged to fight alongside the Avengers when the time came.
It was, objectively, a good thing.
So why did Tony still have this nagging feeling that something was off?
He shook his head, dismissing the thought.
Some mysteries weren't meant to be solved.
Marcus's Apartment
That Night
Marcus lay on his sleeping bag, staring at the ceiling, utterly exhausted but triumphant.
The Exodia gambit had worked. It had WORKED. Tony Stark—TONY STARK, one of the smartest humans on the planet—had been convinced. The "multiple beings" narrative was now accepted fact. His secret was safe.
Well. Safer.
"That was the most ridiculous thing I've ever done," Marcus muttered to himself. "I summoned EXODIA to win an argument. I manifested the Forbidden One because a billionaire was too smart for his own good."
He started laughing.
He laughed until his stomach hurt, until tears streamed down his face, until he was gasping for breath.
"This is my life," he wheezed. "This is actually my life. I'm an interdimensional card game demon who makes alliances with superheroes. I have a 'host of Duel Spirits' backing me up even though it's literally just me. I promised to fight Thanos with an ARMY of monsters."
The laughter slowly died down.
"Wait," Marcus said, sitting up abruptly. "I promised to fight Thanos with an army of monsters. How am I going to deliver on that? I can only be one monster at a time. When Thanos actually shows up..."
He flopped back down.
"Future Marcus problem. That's definitely a Future Marcus problem. Current Marcus needs to sleep for about three days."
He closed his eyes.
Tomorrow, he could worry about the long-term implications of his elaborate deception. Tomorrow, he could figure out how to fake an army. Tomorrow, he could continue being the most ridiculous superhero in any dimension.
Tonight, he would rest.
He'd earned it.
Epilogue
Somewhere in Space
On a throne made of rock and shadows, Thanos gazed upon a holographic display showing Earth's recent events.
The demon. The coalition of spirits. The "unlimited power" that had been demonstrated.
"Interesting," the Mad Titan murmured. "Earth has acquired... new defenders."
Ebony Maw, standing at his side, inclined his head. "Shall we alter our plans, Lord Thanos? These beings appear formidable."
"No." Thanos leaned back, a cold smile crossing his face. "They are merely... obstacles. And I have never been deterred by obstacles."
His hand clenched into a fist.
"The Infinity Stones will be mine. And no amount of 'Duel Spirits' will change that."
The display flickered off.
In the darkness of space, Thanos began to plan.
To Be Continued...