"In order for the character (Loki) to come back up, he had to hit rock bottom. And that really is where the idea of his initial incarceration came from. He starts in a prison, and he’s furious about it because he is in a cell alongside with these other very unimportant Asgardian marauders, abandoned and forgotten, figuratively and literally buried from consciousness. He might as well be dead. And he knows it."