You two were probably involved in a past life, and it wasn't pretty. You likely tried to dominate this person, and they felt repressed, downtrodden and ill-used. Whatever the nature of your relationship might have been -- teacher and pupil, parent and child, or two lovers -- you tried to wield your power over them, and getting involved again in this lifetime only brings that old relationship dynamic back if you're not careful.
It's not that you consciously want to dominate and control them; you might think that you're just trying to help by telling them how to behave, what to wear and so on. If you think this person's life isn't as fully realized as it could be, you might be right, but why is it up to you to get them on track? We each have to find our own path in life, and make our own mistakes along the way. It's better to let someone be who they are and find their own way than to assert your own opinions about what they should be doing with their lives. If other aspects between you support a harmonious, loving connection, this relationship might give you a chance to finally break the chains of the past, but watch out for aggression and domination tendencies, especially on your part.