so what happens to the bottom if the top doesn’t really love him? Will he just get throw...

I am not a 100% sure but he will probably continue the circle and do the same shit to another person to "find" love after the victim becomes like him he will notice he doesnt "feel" what he feeled to his kidnapper for that victim so he leaves too.
Or he might break. Giving him self the fault, getting kinde crazy, trying to find him etc...