caught gf's brother spying on her

Mmm that would be hot. Love the fought of her knowing he is looking, but he thinks she is unaware, and her putting on a little show, trying on outfits, maybe lotion on her body etc.

Love the thought of him going through her stuff and find things in her room, like panties that have some of your cum in them!

If your girlfriend is a hottie and her brother is just a couple of years younger then it would be a suprise if he didn't want to fuck her. (And even more so if you all hang around together, he sees you and her 'making out' and he can even hear you and big sis making the beast with two backs )

Undoubtedly he has been wanking off to her ever since he's been old enough to cum; the close presence of a slightly older female who is sexually alluring cannot be understimated regardless of them having almost identical genes.

The chances are that lil bro has used her panties to wank over and that for some years big sis has been writ large in his sexual fantasies, Even more so right now if he doesn't have a girlfriend of his own right now.

The best thing you can do - in the short term - is to let him listen to you and your girlfriend fucking in order to give him something to get off on. Other than that tease (mind-fuck?) can't your girlfriend set him with one of her friends? (Then you can perve over his woman :giggle.

Umm maybe he wants to fuck her? How old is he?