Anything I can do to improve this relationship?

[wineandroses]

My DB and SIL have a DS same age as my DD (6). They regularly ask me and other family members to look after him overnight (which always turns into full weekends) when they go on weekends away together, or on work-related trips. In the past I didn't mind too much as DD really loves her cousin, though I did have some concerns about how upset he used to get about his regular sleepovers with various family members (not anymore though). However, I am finding it more and more difficult. He is extremely competitive with DD (though not with other cousins), and becomes very sulky and aggressive if he doesn't beat her at everything. He will ask her questions that he thinks she can't answer, just so that he can laugh if she gets it wrong (sulks if she gets it right), and when he thinks no-one is looking he pushes or pinches her. I also find it really annoying that he is so clearly delighted if he manages to upset her, if she hurts herself or if she gets told off. TBH I would rather we saw a lot less of him, but DD loves him and is always making excuses for his behaviour. Have tried talking to DB and SIL, as well as other family members but they all think think I am overreacting and are of the view that my DD is far too clever to let her cousin get the better of her and that he is just being a typical boy. I would really like them to have a nice relationship as DD has no siblings, but he just doesn't seem to feel kindly towards her at all. DH thinks he is jealous as her life is more secure than his. Am I being too sensitive?

I think your DH has hit the nail on the head and this boy is jealous or angry and acting out hisfeelings. However, have you let your obvious disapproval of his parents become obvious to him? Because that might be another motivation for his resentment.

Just re-read my post and I do sound disapproving don't I? Don't mean to, and they don't go away without DN half as much as they used to. I'm a bit sad if he's got a disapproving vibe from me though; must make sure that doesn't happen in future. Anything else you can suggest that might make him regard DD as a friend rather than a competitor?

I think your dh is right too. Tell your family there is no such thing as a 'typical boy'. He wants attention and goes about it in the wrong way. I think you are right to be concerned that he is picking on your dd to make himself feel better, and even more worrying is that she seems to feel that she should validate/ excuse his behaviour. I would want to put off visits for a while, then build them up again gradually with clear rules about what is and isn't acceptable.

W&R: Fair enough. ANother factor is (apparently) 6 year olds can go through a bit of a stroppy stage, particularly boys - I have a nearly-6 DS myself and some of the things - being a bit inclined to be smug when someone else is in trouble, hating to be wrong etc, are things mine does at times.
Do you have an agreement with your SIL and DB about what you are allowed to do discipline-wise when your DN is visiting? What do they do when he misbehaves at home (he must do sometimes)?
Otherwise, are there things that both your DD and DN are interested in that they could do co-operatively?

Lazarush - good point re DD feeling that she should excuse his behaviour - hadn't thought about that but will now!
Solidgoldbrass - your DS and his stroppy stage sounds a lot like DN so maybe it isn't all about DD. When he misbehaves at home DB reprimands him mildly and SIL shouts at him. At our house, DH and I will speak sternly to him and DD re appropriate behaviour etc. DN listens doe-eyed, nodding, whilst DD bursts into tears.
DN not keen on doing "girly things" that DD likes (suggested horseriding, gymnastics, cricket!), but I think it is an excellent idea and I shall ask the DD and DN what they think they might enjoy.
Thanks for your thoughts - makes me think there is something I can do.