It looks very unpleasant - a well-pumped guy is trying his best, and the lady's face is covered with a strange grimace. In general it is not clear - whether she enjoys sex or performs an unpleasant duty! And the body of the lady is not particularly that glitters, and her breasts and nothing at all!
To tell you the truth, considering the age of the brother and sister, it is quite normal that the brother became aroused by the sight of the naked girl in front of him. Maybe what happened next is not part of the plans of normality, but tell me honestly, would you resist such a dark-haired beauty? That's what I mean.
I want two holes