How much do you get for claiming someone on your taxes?

I'm only asking because I used to live with my sister and moved out in April and she claimed me on her taxes instead of my fiances father which was originally the plan. He was going to give me everything he got from claiming me and told my sister she could claim me if she gave me the money but she only wants to give me a portion. Both my fiance, his father and I think it's only fair for her to keep 1/3 of it and her give me 2/3 since I only lived with her for 1/3 of the year. I don't really know how much people get for claiming someone and I've had issues with her stealing money from me in the past and want to make sure she's not going to do it to me now.