Responses
On the one hand i kind of agree...Souicchi is acting pretty juvenile. But I also think he might have feelings for Haruicchi that he's trying to suppress. I think he was trying to goad Haruicchi into kissing him back in order to confirm his hope or suspicion about Haruicchi's feelings. I also suspect that acting like an ass was Souicchi's way of avoiding rejection.
He should just forget that asshole that is "Sou-chan" damn! I'm in a hateful mode, he was the one who invite Haru even when his brother told him to go home. He's a dumbass, Haru deserve someone better!