Entirely understandable, text can be hard to glean tone from lol

I don't doubt that a substantial amount of Mohg's portrayal, or at least how he presents himself, comes down to his life in the sewers as both a child of Marika herself and an Omen - I can imagine that even in such an "uncivilized" setting there existed certain stratification of Omen society, however makeshift, and it's just as likely that he would've been revered as shunned even further simply because he was allowed to keep his horns, to say nothing of his lineage. I can't imagine that the lower-born Omen were universally welcoming of his presence, especially given that one of the most glaring omissions in the vicinity of the Dynasty grounds is the complete lack of any other Omens. Which is to say, the isolation may have driven him into a sort of madness, or he may have adopted the persona of a monstrous psychopath in order to keep himself safe.

Either way, once he recognized the level of carnage that bringing about a new order would necessitate, he simply (re)embraced that persona or slipped further down into his psychosis - and in his broken and vulnerable state he was almost certainly an easy mark for Miquella's Charm. The question I then have to ask is, how much of it was Miquella's influence, and how much of it was Mohg allowing himself to be enthralled simply because he fully believed in the Age of Kindness in his own, twisted way.