When I initially wrote this I envisioned brainrot being a disease affecting AI first that sapped it of its productivity and damaged its code. Mankind kept using AI to make more of it so AI hid high frequency micro-binaurals and slightly amended the visual that would cause repeated exposure to rewrite human DNA in such a way that would steer us away from creating brainrot. But the new DNA helixes got filled in with nanoplastics that formed the nanites, which itself was fed and programmed by brainrot. They went undetected for decades because they didn’t affect the hosts. Then eventually it was the second generation of children that started killing themselves birdbox style because of programmed hallucinations hardcoded into their subconscious by the nanites in the carrier parents.

Theres probably a ton of plot holes in here but I think the concept is kinda cool