If I found out my sister was a slut, I would have pulled her in the asshole, too. For these guys, getting their asses handed to them is commonplace. Although for the look, they break for a few minutes, but when a couple of drops of lube appear - they quickly sit down anally on the phallus. So this little sister is nice to feel like a courtesan, to show off all her skills in front of her brother, to let him cum in her ass. Every bitch dreams of being the best at it.
From the front as well as from behind - well, absolutely flat woman. Only one advantage is obvious - well-designed orifices. And of course due to the flat buttocks it's very convenient to pull your partner in the anus, even without bending her over. And I don't see anything else interesting in this lady! The man is basically of age, so probably the determining parameter for him is the age of the woman and the possibility to work her anally!