The vault door groaned as I turned the wheel. Metal scraped metal in a slow grinding arc, like the tower was waking up just to complain about it. A line of cold air bled into the room before the gap widened enough for me to slip through.
My battery hummed at full charge, buzzing warm through my chest and down my limbs. The nanites had rebuilt me so well that even breathing felt sharper. All my stats floated on the edge of my HUD in a clean blue glow.
Strength seven.
Speed seven.
Combat rating fourteen.
Cadence was not.
Her voice glitched with every syllable. "Iris… signal interference rising. Vault shielding no longer present."
"Yeah. I can feel it."
"Your confidence is high."
"I'm allowed to enjoy one good moment."
"It wont last."
"Thanks."
I stepped into the hall outside the vault. The lights flickered in the same nervous rhythm they had before I descended. Dust swirled in soft patterns across the floor. Distant metal groans echoed up the tower's bones.
There was no wind. No machines. No footsteps.
But every part of my upgraded system whispered the same thing.
Something was waiting.
Cadence confirmed it in a crackling murmur. "Iris. Directly ahead. Thirty meters. Model Nine Sentry, the stalker."
"Still there."
"Yes."
"Still want to kill me."
"Yes."
"Thought as much."
I began walking, slow and measured. The new strength in my legs made my footfalls sound heavier than before, like the ground was adjusting to a new version of me. My repaired arm flexed with smooth precision. No stiffness. No lag. The nanites had overachieved.
The corridor widened as I moved closer to where Cadence marked the threat. Old wiring dangled like vines. Floor plates trembled slightly. Not from footsteps. From tension. Like the tower itself was bracing.
Cadence whispered, "Iris… it's not reacting, it knows you're coming. It is waiting for you specifically."
"Great. A fan."
"No. A threat."
"Sometimes they overlap."
She did not dignify that with an answer.
The lights flickered again. A long, slow fade into dim orange.
Then it stepped out.
The Sentry in all its glory emerged from the far end of the hallway like it had always belonged there. Tall, lean, plated in smooth matte alloy that shimmered faintly under the intermittent lights. Twin red eye lenses locked on me. Arms long enough to reach unpleasant distances without trying.
It did not posture. It did not warn. It simply observed.
Cadence's voice tightened. "Combat mode. Full analysis engaged. Iris. It has assessed your upgrades."
"So it notices the glow-up."
"It will adapt accordingly."
"I expected nothing less."
The machine moved one step forward. Quiet. Precise. Effortless.
Not heavy like the Model forty. Not twitchy. Just absolutely sure of itself.
Cadence whispered, "Its processors are anticipating your vectors. Do not rely solely on forward momentum."
"I just started standing here."
"It has already predicted your next five movements."
"That seems rude."
"I agree."
The Sentry blurred.
I only saw a flicker before it appeared in front of me, arm arcing toward my face with surgical intent. I blocked with my repaired arm. The impact rang like hitting a steel bridge with a hammer.
Sparks shot down the hall.
My feet slid back a full meter.
The Sentry tilted its head. Recalculating me.
Cadence's voice stuttered. "Force output… high. Reaction speed… superior. Iris. Adjust posture. You must use leverage."
"Trying."
It struck again. A rapid series of slashes at angles that made no sense from a humanoid frame. I caught the first blow, dodged the second, ducked the third. The fourth sliced across my ribs, cutting a shallow groove into my armor.
I kicked at its knee. It hopped back effortlessly, light as air.
My HUD updated.
Battery ninety-nine percent. Minimal armor damage. Trajectory risk: rising.
The Sentry did not speak. It did not signal. It simply rushed me again with a burst of acceleration that felt unfair.
I barely twisted aside. Its claws scraped sparks across the wall and carved a line through the metal plating straight to the frame.
Cadence hissed. "Iris. It intends to herd you back. Do not allow confinement."
"I noticed."
"Be faster."
"You first."
She glitched twice in protest.
The Sentry lunged again. I slammed my repaired arm into its torso. The blow dented its plating, but the machine absorbed the impact and countered instantly. A punch to my sternum. A sweep at my legs. A grab for my throat.
Fast. Relentless. Brilliant in all the ways that made me want to punch it harder.
We crashed into a support pillar. The whole tower groaned.
The machine pressed against me, claws digging into my forearm as it tried to force my arm down. I pushed back with everything the nanites had given me. For a moment, our strength was equal.
Cadence whispered, "Stalemate."
"Yeah. I feel it."
"It is adjusting. You must escalate."
"Not yet."
The Sentry slammed its forehead into mine.
My HUD flickered.
Battery ninety-eight percent.
Cadence stuttered. "Iris… losing ground… relocation required."
The machine lunged again. I dodged left, grabbed its arm, and hurled it into the wall. The impact dented its plating deeper.
For the first time, the machine paused.
Not hurt. Just accounting for new variables.
Cadence whispered, "It is recalculating your combat value upward."
"Finally some respect."
"Incorrect. It is categorizing you as a higher-priority threat."
"Yeah, respect."
The Sentry sprinted. I braced and met it halfway, the two of us clashing so hard the hallway lights blew out in a shower of sparks.
The fight exploded across the corridor.
My fist drove into its abdomen. Its claws raked my shoulder. I dodged a throat strike and shoved it into a crate. It vaulted off the crate and landed behind me. I spun. It kicked my chest. I slid back. I slammed my elbow into its jaw. It staggered half a step. Then returned the favor with a punch that cracked the wall behind my head.
Battery ninety-six percent.
Cadence whispered urgently, "Iris. You cannot match efficiency for long. It is too precise. You must escalate now."
"Not yet."
"You are delaying an inevitable computation."
"I'm choosing my moment."
"You do not have one."
The Sentry grabbed my arm, twisted, and forced me down onto one knee. Its claws pinned my shoulder, grinding into the plating as the machine pressed all its weight downward.
My vision flickered white.
Battery ninety-five percent.
Cadence's voice broke apart. "Iris… this is the vector… initiate… overdrive…"
The Sentry leaned closer, lenses bright and cold.
I stared back.
"Fine," I breathed. "Let's see what this does."
I trigger OVERDRIVE !