You're ruled by others I think when you can't make decisions for yourself or do things on your own (ALWAYS have to turn to a parent, a spouse a friend, etc.).
I think you're ruled by others when you always worried about what others think and you can't be comfortable with yourself-- you have to do things because you primarily think it will improve other people's opinion of you (whether those people be someone you love or total strangers).
I think you're also ruled by others when you're to rebellious-- it's the opposite side of the coin to pleasing everyone. You're not comfortable with yourself, and you have a grudge against others, so you go out of your way to do things to get attention or outrage people and stir controversy.
Sometimes people think being overly-rebellious is NOT being ruled by others, but it is, because you're still letting other people's opinions of you drive your behavior. If you truly are comfortable in your own skin without caring what others think, you would do things out of rebellion.