Responses
This one, kinda?
Top is not a crazy psycho, but the couple is definitely not a healthy pair.
https://www.mangago.me/read-manga/mobius_strip/
beta
I need bullied seme x bully uke so baaddd, one where it turns out the victim (seme) is actually this insane psychopath and gains this strange obssession w uke. Stories exactly like "Doukyuusei A" or "Boku wa Ninkimono"