#muzan voice it's me ingo the first demon speaking to you inside your brain listen to me kill your brother we don't need him-

[nemesis-is-my-middle-name]

we have to discuss muzan powers goddamn

Did you know he can implant his Consciousness into demons?

he can just live inside their brain. Rent free. if they have enough blood. Even after he dies.

Not to mention that ones thoughts aren't even safe.

As the progenitor demon he is only demon capable of inflicting life-threatening wounds capable of completely destroying the cells of another demon without the need of the swords or sunlight. (Direct quote from the wiki)( I'm trying not to confuse you by seriously fact-checking now)

So what I'm getting is that Ingo can also do permanent damage sort of deal via by breathing

okay here is what i'm thinking and this requires a little editing of the exact clauses and rulesets of muzan's powers but shh. what if, being cornered by the hashira, he decides to essentially let them think they're destroying him, and transfer his consciousness to ingo's body, one demon they won't kill if they don't think he's a liability. and then he just... waits, patiently, biding his time, knowing that eventually the perfect moment will come where he can destroy the demon slayer corps, comprehensively, once and for all