TBH I wasn't expecting Ahaiyute to begin with since from what I remember (though I only read through this series once) he still fought against it & kinda won- albeit as the sole survivor- until the whole swarm of wannabe angels descended immediately afterward. I wasn't expecting the doppelganger to transform into himself since that seems like a weak ass tactic but it does make sense that the strongest negative emotion he's ever felt was just despair. I'd've just thought it'd transform into like... the piles of dead people he feels guilty about, or something along those lines? Like if you wanna guilt trip someone, the classic "ghosts of the past" schtick seems like it'd be a lot more effective than what essentially boils down to the schoolyard bullying "'bOo HoO i'M rOnAn I'm SuCh A fAiLuRe' that's you, that's what you sound like idiot" tactic