He needed a cock and he didn’t care that it was his brother’s
His little sister was horny that day, maybe too much. Normally she would have masturbated, but there was something she wanted more than touching her own pussy. Her brother was right in the next room, and she was sure that if she tried to seduce him he would accept. She approached while the boy was sleeping and he woke up. There was her little sister smiling with her skirt and wet panties. She wanted his cock and he knew it, so he didn’t have time to take it out. After playing for a while the guy ended up putting it in her tight young girl’s ass, she enjoyed it like a pig. And he not only enjoyed the fucking, but also the fact of feeling his brother inside his ass.