Rocket's GOTG Vol. 3 Story Was In The Works Since Guardians of the Galaxy

James Gunn explains that the Guardians of the Galaxy story has always been leading to Rocket's origin, which is at the heart of Guardians of the Galaxy Vol. 3. Rocket has been a part of the Guardians of the Galaxy since the beginning and has been a key member throughout their journey. In Avengers: Endgame, he and Nebula are the only two left to help protect the universe and save their friends. Guardians of the Galaxy has been dropping hints about Rocket's past since the beginning, but his origin hasn't been fully explored until now.

Source: Screenrant