Is there a word/idiom/expression to refer to someone whom I have helped a lot but doesn't reciprocate any favors even though they are capable of helping me? For example:
I have helped Peter a lot when he had issues, but he stiffs me when I am going through a tough time. I thought he would help me, as I had helped him a lot in the past. He is ___________.[Someone who doesn't reciprocate favors]
I am looking for a word/idiom/expression other than selfish.