In all their iterations, the central theme of the Guardians of the Galaxy movies has been about chosen families and strong friendships. However, there is another theme that is worth mentioning: that of family abuse. Almost all heroes are influenced by the complexity of their past, but what separates the Guardians from other superhero teams in the Marvel Cinematic Universe is how they have been mistreated by their own family members. Gamora and Nebula were taken, raised and abused by the Mad Titan Thanos. Rocket was experimented on by the High Evolutionary, who also killed Rocket's friends. Finally, Mantis was a servant for most of her life, enslaved by her own father, Ego.
Source：https://www.cbr.com/guardians-of-the-galaxy-movies-abuse-healing-themes/
