I don't see the wolf as too bad. He took care to not hurt Koichi when going through the window. Even tho he didnt need to, he was patient enough to not beat Koichi up when keeping him captive.
And yea, he messed up by touching Koichi like that, but he thought Koichi was just "in heat" and not poisoned, he didn't seem to want to do a lot more to him other than just making him c*m as asap so he would get better, and also he didn't know Koichi and Caius are lovers.
So yea, he isn't a good guy per se, but he isn't rotten either.
Anyway, why the he** am I reading this!? I never read yaoi, only soft bl/shounen ai
