Come on, Usagi did deserve that. He kind of groomed Misaki to be his uke since he was in high school..Takahiro didn't entrust his bro to him for that. I know 13 is the age of consent there, but still, he was jerking Misaki off everyday. I am glad they grew with each other to the relationship they have with Misaki a true adult, but a part of me wonders if Misaki would've dated girls if he was left to explore his sexuality without the grooming.
Think of it from a father's perspective. What if you entrusted your kid to your friend. How would you feel if they ended up getting together with your kid? Not so happy right? A lot of people would have a hard time approving even if it's just a normal guy/girl relationship considering the age difference and power dynamic already, let alone a homosexual relationship. Considering how young he is, he might be making the wrong choice to them as well.

If that was MY boyfriend, I’d call my brother so fast and cuss him out(⊙…⊙ )Like I get HE invited YOU out but you still don’t hit my boyfriend Σ(っ°Д °;)っ if we had no relationship whatsoever then that’s not my business...but if he’s MINE! We got an issue if you wanna go swingin fists. I thought he’d be upset when he saw his brother hit him but I guess not. He’s gonna be timid till the fuckin end. I’d be pissed even more so cause HE suffered while he raised him all by himself too. ( ̄へ ̄)