He doesn’t care that it’s his brother when he wants to fuck
Sometimes we think of the needs, as sublime things, of the spirit and not of the body. Beyond the things your brain may want, the truth is that the body asks for things and you have to give them. That or suffer from fighting against your nature. And this is something that the young girl understands well since she doesn’t care that he is her brother when she feels like fucking. She only gives him a cock suck and the guy also understands that if his sister wants her pussy to be fucked, he doesn’t have to go out on the street to look for her having a male at home.