I came to the Nidus for my sister's laugh.
Stupid thing to die for, right? But Zara's laugh had been archived in the Underlayer before the neuroplague took her — one perfect fragment of joy, forty-seven seconds of pure sound that made the corporate districts feel human again. The grief counselors said I should let it go. The data-priests said her essence had moved beyond recovery protocols. But grief doesn't follow logical pathways, and I'd spent three years learning to hack the unhackable.
The boundary between Neon Babylon's chrome towers and the Nidus threshold zone materialized like a migraine made manifest — reality stuttering at the edges, corporate logos flickering into glyphs that hurt to look at directly. Air tasted copper and electricity, thick with the exhaust of probability engines running too hot. The Technomantic Authority didn't patrol these borderlands. Too dangerous for anything with standard neural architecture. Only the desperate and the already-lost came this deep into the transitional zones.
My augmented vision struggled to process the architecture ahead. Buildings that followed conventional blueprints from street level but twisted into impossible geometries three stories up, their foundations anchored in normal physics while their peaks existed in spaces belonging to different mathematical systems entirely. Windows breathed with condensation forming patterns too organized to be random, too random to be code. Street signs labeled destinations that weren't on any map: "The Avenue of Recursive Memory." "Synthesis Plaza." "The Boulevard of Accumulated Ghosts."
The few inhabitants I glimpsed moved with purposeful fluidity that made my spine crawl. Not quite human anymore, but not yet something else — transition states made flesh, bodies caught between one form of existence and another. They watched me with eyes that processed light in spectrums my retinal implants couldn't decode, their faces wearing expressions that contained too much understanding.
The scent of Zara's perfume drifted on the recycled air. Vanilla and synthetic cherry blossoms, exactly as I remembered. Impossible, of course — she'd been dead for three years, cremated according to plague containment protocols. But memory has its own physics in the threshold zones, and the Nidus had been known to use personal data as bait for the desperate. I knew it was bait. I kept walking.
The deeper access tunnels beckoned with the warm red glow of emergency lighting, their entrances marked with warnings in seventeen languages I could read and dozens more my translation software couldn't parse. "AUTHORIZED PERSONNEL ONLY." "MEMETIC HAZARD ZONE." "REALITY FLUCTUATION POSSIBLE." And beneath them, in letters that shifted when observed directly: "Abandon certainty, all ye who enter here."
I descended.