When a brother, albeit a stepbrother, sleeps with his sister in the same room, sex between them will happen sooner or later. The smell of her body, her rounded forms will make any guy masturbate. And the pictures of her in his smartphone turned his sister on. She felt like an adult magazine star. And she wanted to thank her brother for the experience. In her own womanly way... And it was satisfying for both of them.
The girl is so flexible that she can give pleasure in almost any position. And such a huge dick didn't embarrass her, it fit well in her mouth and inside her. I especially liked the first blowjob pose, when she curved up. I should try that too.