Some people are willing to follow someone who is no good to them but they just follow them even when he is using them and they know it very well but still they are committed to obeying him. For example, they know that them being hurt will not move that person and that they are inferior to him but they do everything to not upset him. Is it clingy, sticky or what?
The person you describe sounds a little masochistic (adjective). In other words, he is a masochist (noun). There is not necessarily a sexual component to this kind of masochism. I'm thinking of the third definition of masochistic:
- A willingness or tendency to subject oneself to unpleasant or trying experiences.
As for why a person will endure all kinds of abuse, well, there could be any number of reasons. Perhaps a low self-image is at the heart of the kind of masochism you describe. Perhaps the issue is powerlessness and the feeling that nothing can be done to fix the situation.
Or perhaps the victim fears the victimizer's reprisals, almost as if the person in control is extorting the victim, and the victim fears what will happen if he protests against the abuse.