Brandon watches Zack and Madison make out until he can't resist stroking his cock

Brandon watched from the darkened living room, his cock throbbing inside his shorts as his sister made out with Zack.

Zack and Madison were silhouettes against the faint light of the sky. Through the partly-open door, he heard sighs, moans, kissing sounds, and the occasional shuffle of a foot to stay balanced as the make-out session got more intense.

It was less graphic than when he'd first caught them together, with Madison practically flaunting her cock-filled cunt at him as she rode Zack on the couch and shouted at him, insisting on having her way.

Brandon sighed. If Madison was gonna throw herself at someone, at least Zack was better than most. Zack was kind of the perfect choice if his sister had wanted to get his goat. He would have picked a fight with Kurt. But Zack? That would make Brandon the bad guy in everyone's book.

Madison was starting to moan. Zack was feeling up her tits, Brandon thought. Whatever was going on, it was working for Maddie. He could see her hips rocking. Maybe he was touching up her pussy now.

Brandon's cock stiffened, sticking out the leg of his shorts like the last time he'd watched.

"The hell," he muttered. He tugged at the leg hole, letting his cock spring up, and stroked it as he watched Zack and Madison's silhouettes moving against one another.

"Oh!" Brandon heard a feminine voice behind him.