Your child with this problem is well along the way to social isolation. In many ways, children who are having problems with fighting and getting into fights are getting along better than the child who just stands there and takes it. In the give-and- take, the child with this sign only takes. His Parents may have taught him to be non-aggressive for religious or moral reasons; but if so, he has a proud and self-controlled quality about him. The sign is there; but it does not have a negative quality about it. A passive, "I have to take it," attitude is more likely. It is a whipped-puppy kind of thing. The youngster is either afraid to stick up for himself or all the spunk has been taken out of him. Either way, it is a serious problem.
It is very difficult to help a child with this sign. You can, nonetheless, do two things. First, Try to get him to stick up for himself, especially in situations with adult supervision. Next, when he does not stick up for himself at home, be slow to come to his aid. Home is a very good place for him to practice.
As a child exhibiting this sign begins to stick up for himself, he likely uses primitive methods. He may hit, yell, or try other things that are problematic. If so, you can say, for example, "You hit your sister. I'm proud of you for sticking up for yourself. You have the right idea; but hitting isn't your best choice. You cannot do that. Next time, try just yelling at her. I don't know for sure if it'll work better. It's just something to think about, But hitting is not okay."