He'll probably just take the teasing, and dish a little back. Considering she moms almost all the teens he's met.

Oh! Another little fun thing is that she probably knows by now is he... doesn't have much of a family, save Xion and his original (the one he shared a room with in the Tower, that is; the one from his original world's timeline won't remember a thing save what happens in canon). Very vague memories of Riku's family but he wouldn't be able to pick them from a crowd.

Also Vexen is a jerk of a creator so he doesn't count that as family.