YEAHH. it's just all super suspicious, like why react like that when your friend is in trouble?? and overall just be out of pocket, not like how we first met them but as the story goes on they just show more weirdness, and them paying someone to throw trash down including the trash bin would make sense cause I assume they probably do have the money to do that, and the 'friends' just don't seem to care about the bullying as normal friends would care if that makes sense
The boy is very nonchalant bit definitely an accomplice, he seems air-headed and like he doesn't care, he seems to be following what the girl says but we don't know maybe he's weird or has his own motives. The girl is guilty as hell, but I wonder if they would do the same thing when she hangs out more with the black haired vampire, doesn't really seem like it

I feel like it's those two especially the girl