Yuffie might try to steal things from Sho, just for the challenge. If she finds that he has a lot of Gil from the factory she will go after that and will first look in his sock draw.

As for Gen, well, she really wants to steal his copy of loveless just to be a jerk and the moment he confronts her she would just smile and be like. "I just wanted to get your attention." If you don't know, Yuffie might have a small crush on Gen.

Let me know your thoughts! Also no worries about what she steals since you can get it back if you wish.