Fan Casting Bruce Banner in MMU/6.: The Avengers (2012)

Bruce was founf by Natasha and she recruited him to the team, but primarily as a scientist and expert of gamma radiation. On S.H.I.E.L.D.'s Helicarrier he was controlled by Loki and transformed to the Hulk. The green monster fought against Thor and when the Helicarrier crashed he fell to the ground and went missing. In the final battle he joined the fight and smashed as much of Loki's army as he could. After they win, Banner got protection by S.H.I.E.L.D. so he had not to flee more.