It's a long story but I'll make it as short as I can I've know my step son since he was five and I've treated him like my own( used to tell him when he was naughty I don't anymore!), and over tried at times, spoilt him sometimes more than my own children, just try to get him to like me.. I have two children of my own and my partner has two when we met my eldest step son is good he's on and off but stuffers from mental health issues from my other step sons mum when she used to live with him anyway he lives with me and his dad full time now.  My other sept son who the question is about, is the one the problems have been with he's really aggressive and angry all the time, extremely spoilt by both his mum and dad I don't suspect and fowl play with either of them no abuse etc so he's not acting out through that.  He has beaten my children, my nephew up serveral times and argues with them they are at least two years and younger than him.  He calls me a fat f&c@ing p;)ick and other swear words all the time over nothing or maybe because I've said no or because I've asked him not to call my sons.  He's made threats towards me and tried to smash a glass window to go for me, he's filmed my underwear drawn and my belongings to show his mum.  I have videos were he says he wants to hit me, but nothing has gone on at the time it's always out of no where.  I'm always polite as everything I say to him no matter what it is he Tells his mum I've said something nasty and she phones having a go at dad.  It's getting worse and worse and unbearable to live with but I adore my partner and we have a child together who doesn't deserve seperated parents just because of his brother behaving this way.  My partner does try (sort of) but I'm not sure what else he can do? My step sons mum is a social worker, he obviously suffers with his mental health badly As he is never happy I've not seen him laugh or smile in years, but unsure what to do??? Ive tried so much to make him happy I've told dad to try things but nothing seems to work please help!