The sisters are those pussies, which you try to satisfy, see how he fucked them, and they do not give a damn, go around smiling. I think that all was filmed very cool, it is clear that the picture worked hard, and the main character perfectly grilled these young chicks, who apparently have not had sex for a long time, as they give him a good hand, the cock came to their liking, moaning like wild.
The girl probably hadn't had sex in a long time, or she really fucked up, since she decided to please her old grandfather with a blow job. But he turned out to be a hot man, so he continued.