A person who does you a favour then uses it against you? [closed]
What is the word for a person who does you a favour then uses it against you?
I'd call that person manipulative.
Exercising unscrupulous control or influence over a person or situation:
she was sly, selfish, and manipulative
Reference:
http://www.oxforddictionaries.com/definition/english/manipulative
The act of doing something for someone and then expecting something in return is usually called keeping score. I don't think there's a noun that exactly defines a person who does this--you might call them scorekeeper.