Responses
I would not called his actions in Brutal purely vigilante, since it can be seen that he enjoyed torturing his victims (taking pictures, dancing, laughing, etc.). So yeah, dude has always has some few loose screws, I think it's just more blatant here.
From Brutal, I thought Dan was the vigilante type. Yes, he committed horrible crimes, but all his victims deserved it. But from what we’ve seen here, he seems more like your regular old asshole.
So either A) The author changed his character around a bit for Brutal.
Or B) There’s a lot more going on with the main character’s family. Maybe they’re not just innocent victims.
I mean we’re only a quarter of the way in, plenty of room for plot twists :)