My ds is just 3, and in the last few months his persistence and assertiveness have really started to come out. My parents had him overnight last night (first time in a few months) and my mum commented to me that he was 'naughtier' than he used to be - not really bad, but just more disobedient and determined to get his own way. If they told him off for anything, it was like water off a duck's back. She is thinking that they will have to resort to giving him time-outs, as they don't know how else to handle it. He also used to be the quiet little child that always had his toys taken away from him by other children, and now I've noticed that he's starting to take other kids' toys away from them, and I've started to reprimand him for doing it.
Does this sound pretty normal or is my ds turning into one of those horrible little children??!! () He is VERY persistent, if he wants to do something and I say "No", he will complain and then keep coming back to ask me for the same thing several times. It's all very tiring and I think my parents were a bit taken aback by the change in him. Hope this is all just part of his age/stage.