As I thought, saving Vision for later trailers. Couple things, Widow was experimented on? Whoever that woman in the cave was, it looks like the same water hole that Thor thrashes in. That coupled with it seems like he regains his thunder capabilities or something, do we potentially see a Unworthy Thor in the movie, only to see him get his powers back? That would jive with why he isn't fighting Hulk instead of Iron man. They hammered the Worthy thing in the Lounging scene.
Maybe widow and hulk both were. hulk had some darkness under his eyes during the hulk buster fight. maybe he was driven mad again...which would suck imo. Two movies and he gets manipulated twice?
Well Widow looks young when they elude to her getting operated on. She seems to be a central story in this flick. It does look like Hulk gets mind manipulated, and if i were take a guess (im usually pretty good at this) I think Scarlet witch is behind it as they (QS and her) are aiding Ultron in the beginning of the film. Ultron kinda rips the team apart and they go their separate ways on fools errands. All which is a ploy so he can buy time to create his New body. By the time the team realizes what he is playing at, it's too late. He then proceeds to wreck them killing 1 or 2 (here's looking at you Hawkeye and mayyyybe QS) they find out they are outmatched, so they become friends with Scarlet witch, explaining to her that Ultron used them leading to her bros death and create Vision. Of course there will be other threats going on to keep the whole team busy in the climax, but that's the gist.