Board Thread:Questions and Answers/@comment-32039927-20171010172534/@comment-32931283-20171011203553

and it was confirmed in that "talk" (which has major spoilers) that Rocket was indeed abused horribly, he is constantly reminded of how different he is etc..while not completely canon I also recommend you play TellTale Guardians, it is set in movie-verse and shows EXACTLY why Rocket acts the way he does..

Guardians is a dark, mature title.. under all the comedy.. Rocket does what he does for a reason and trust me, they aren't completely out of malice.