>>54475809I would agree with that if it wasn't so one-sided on Carmine's part. Most healthy sibling relationships do have a lot of stupid fights and arguments and some light-hearted bullying, but whoever takes it also has to be able to dish it back, which Kieran doesn't really have the chance to do at all.
Regardless of Carmine's intentions, she constantly belittles him, even in front of people they'd just met, and led him to develop incredibly low self-confidence that she takes advantage of to "protect" him some more. She constantly thinks she knows better than him and insults him so he doesn't argue back too much. We know it's her way of showing care and protecting him, but again, intentions don't exactly matter here.
Kieran is so used to being the weaker of the two siblings, the one everyone ignores for Carmine. Carmine literally talks about how pathetic he is and pushes him around to make decisions for him in front of strangers which only compounds that. Once Kieran finds someone who he thought he could trust, someone who HE could be friends with and not just as Carmine's tag-a-long, you (the player) starts keeping secrets from him with Carmine.
It makes complete sense to me that he snaps as he does.