So ... my partner and her four year old daughter have moved in with me and my 16 year old son (who lives with me part time). They don't know each other well and the age gap is such that they have no shared interests. I suspect that for my son, the girl is just an irritating invasion of his space, and he has no incentive to develop any kind of relationship. What joint activities might both of them enjoy outside the home, without it seeming forced?