Ds is 3 (says he loves his sister - sometimes ) He is so rough in his play with her though that she is constantly in tears and comes running to me (she is almost 18 months). The only time they are really sweet together is just before bathtime when they run about chasing each other, laughing and cuddling. The rest of the day he is constantly whacking her, tripping her over on purpose, pulling her to the ground and generally being really aggressive. I have to be out of the house most of the time when they are both up as that is the only time when it stops. I think this is partly a combination of him being a very boisterous child and partly annoyance that she gets in the way of his games and takes my attention away from him. She is starting to fight back as she was sitting on my lap reading a book the other day and he tried to muscle in - she walloped him. I just thought 'good on her' Any ideas for strategies to deal with it?