The Simon attacks Amy thing wasn't as bad as I thought it was going to be. She was being a Tracey clone at the time. Tracey really needs to look in the mirror before she has a go at Leanne. She seems to expect Steve to do 95% of the parenting and slags him off if he doesn't do it. Leanne would be well within her rights to wash her hands of Simon (she never adopted him, did she?) I can't think of many step parents who would stand by a step child if they were the subject of their abuse.
Simon has said about everything else to hurt his family than to point out that Amy isn't Ken's real granddaughter. I'm surprised this hasn't happened yet.
There is definitely some history with Robert and in a few scenes, it seemed to me that he was possibly the abused who became an abuser.