An impossible transformation
Bruce Banner is one of the original members of the Avengers in the saga of the same name. At the end of the second opus, Bruce Banner remained transformed into the Hulk and let himself drift aboard a quinjet that left for space. Thor found him in the movie Thor Ragnarok where he became a gladiator in an arena on an alien planet. He manages to calm him down and finally make him become Bruce Banner again for the first time in many years. At the end of the movie, they are both on a ship back to Earth. At the beginning of Infinity War, their ship is attacked by Thanos but Thor manages, with the help of Heimdall, to create a passage to send Bruce Banner back to Earth. Unfortunately, it seems that he can no longer transform into the Hulk, even when he is under great stress. He’ll have to help the Avengers by taking control of one of Tony Stark’s robots to try to fight Thanos with them.