Avengers: Age Of Ultron Spoilers - 16 Things We Know Will Happen
4. Scarlet Witch Turns The Hulk
Obviously, Bruce Banner's fears that he is not in control have to feed into something, and given the fact that the trailers have heavily featured the fight sequence between Tony Stark and Big Green, it looks like he goes fully unhinged. There's a possibility that Hulk's loss of control - which probably comes a lot earlier in the film than the expected finale set-piece - is a direct result of Stark's meddling with his genetics, but it's more likely that Ultron pin-points his weakness and uses Scarlet Witch to turn him and free the beast before she aligns with the Avengers. That would explain why Hulk flips and fights Tony, despite them being close friends, and it's another point that the LEGO tie-in sets have seemingly confirmed. In their Hulkbuster set, LEGO have included Scarlet Witch and the pose on the box does seem particularly loaded (this would also explain why Bruce is so broken by the experience)...
