The broken, saltwater-logged hoverboard sat in a corner of the house like a tragic, grounded bird. Seeing the constant, sorrowful glances Ren sent its way, Ganyu's heart ached. After a few days, she could stand it no longer.
"We'll make a new one," she declared, her voice full of a gentle, determined resolve. "A better one."
And so, the quiet house on Feiyun Slope was once again filled with the low hum of adeptal energy and the focused, excited chatter of invention. Ganyu, using the communication sigil, relayed their material needs to Xianyun, who, from her mountain workshop, would procure the rare alloys and components and have them delivered with a quiet, almost magical, efficiency.
Rebuilding the hoverboard was a faster, more confident process this time. They knew the design, they understood the principles, and they worked together with a seamless, practiced harmony. Ganyu, under Ren's patient tutelage, had become a surprisingly skilled assistant, her adeptal precision perfect for handling the delicate internal wiring.
But as they worked on the familiar, beloved project, Ren's mind was already leaping ahead, grappling with a new, far more ambitious, and far more dangerous idea. The encounters with the Harbingers, the battle with Osial, the knowledge of Childe's Delusion—it had all coalesced in his mind into a single, burning problem that demanded a solution.
The Fatui's greatest advantage was the Delusion, a technology that granted immense, Vision-like power to those without the favor of the gods, but at a terrible, life-draining cost. It was an unnatural, parasitic power, a shortcut that consumed its wielder.
Ren, the boy who had invented a heater to bring comfort and a refrigerator to prevent waste, looked at the Delusion system and saw only a profound, tragic inefficiency. It was a flawed, ugly design. And he believed he could build something better.
Late at night, long after Ganyu had gone to sleep, Ren would be awake, his small desk illuminated by a single, soft lantern. He was not drawing schematics for machines of convenience anymore. He was drafting a blueprint to challenge the very foundations of the Fatui's power.
His new project was a device for the analysis and manipulation of pure energy. He had experienced it himself, the way his own body, without a Vision, had absorbed and repurposed Ganyu's Cryo energy. He theorized that it was possible to create a device that could do the same, but for anyone.
His notebooks became filled with complex, theoretical diagrams. He was designing a device, a "Resonance Chamber," that would be capable of absorbing the ambient elemental energy that was latent in the very air and earth of Teyvat. The greatest challenge was not in the absorption, but in the refinement and storage.
His design centered around a core component he called an "Elemental Conduit." It would be an artificial, crystal-like lattice, forged from a complex alloy of crystal marrow and noctilucous jade, designed to be a blank, stable vessel, capable of holding a charge of pure, refined elemental energy without degrading.
His main theory was to use the concept of what was typically known in his world as a thermos flask. The ability to store heat energy with isolation from the environement to not only keep it stable but also long lasting.
The concept was revolutionary. If it worked, it would be a true artificial Vision, a way to grant elemental power without needing the approval of Gods.
But his true motive, the core of his ambition, was to create a direct, superior alternative to the Delusion.
"The Delusion is a parasitic system," he wrote in his secret notes, his handwriting a neat, precise script. "It draws its power from the user's own life force, a finite and precious resource. It is a flawed, destructive feedback loop."
His design was different. "The Elemental Conduit," he continued, "will not be powered by the wielder. It will be powered by the world itself." His device would draw ambient energy, store it, and then allow a wielder to access it, acting as a simple, external battery of elemental power. It would be a symbiotic relationship with the world, not a parasitic one with the user. It would grant the power of an element without the deadly, life-draining side effects.
He knew the dangers. This was a technology that could change the balance of power in the entire world. It was a direct challenge to the authority of the gods and a mortal threat to the Fatui's military supremacy. But the fact that several lives could be saved by giving an alternative to delusion was perhaps the only thing in Ren's mind at that moment.