Stepson is trying too hard to please everyone!?

My stepson, 13, will do anything and everything to please his father and real mother. He will ask to take out garbage, mow the lawn, clean his room without being asked and tries too hard to help everyone - doesn't seem right for a teenager but he's been like that since I've known him - 5 yrs. His father doesn't seem to notice it and doesn't see anything wrong. It's very annoying because stepson seems very phony doing all of this. My nerves are gone when he's around and I always try to avoid him - not a healthy attitude but I don't know what to do?