First of all, this is my first article, and this is just speculation or better said ; a theory. So don't go Ape shit if you disagree with what I THINK, might be.
As many of you know, William Hurt, who played General thunderbolt Ross in marvel's "The Incredible Hulk" Is reprising his role as the general once again in Captain America: Civil War, which comes out next year.
Now, Who gives a care you might say, who's that?
Well in the comics General Thunderbolt Ross is an enemy and constant annoyance to Bruce Banner and specifically to his hulk persona, chasing him with tanks and shit. Later on though, Ross becomes the red hulk, According to the Marvel.wikia. Page, " It was revealed that Ross and Doc Samson had a hand in the creation of the Red Hulk, assisted by A.I.M. and the Intelligencia. The true extent, revealed during the Intelligencia's invasion of Washington, D.C., was that Ross had become the Red Hulk to further his vengeance against Banner and as part of a promise made by the Intelligencia to revive the then-thought deceased Betty."
Now the other day, a couple days after the announcement of the actor reprising his role as Ross, I watched Iron Man 3, because that movie is sick and I had just bought it so, yeah... As I watched the movie and saw the extremis soldiers again and again with their lava looking blood, I suddenly got an awesome thought, 'what if the red hulk is somehow made using the extremis serum thingy and somehow merged it with hulks irradiated blood' I told my brother and we geeked out like crazy. (Of course, red hulk is not confirmed to appear in civil war just so you know, but his alter ego is).
If you read the description I put, you notice that A.I.M had to do with the creation of the red hulk in the comics, and as you know, in the movie IM3, A.I.M was the company behind the extremis soldiers. In the comics the red hulk's blood is lava hot, and apparently the madder he gets the hotter he gets LOL, so there's that.
Now this is in no way hinted at anywhere, but I believe its definitely in the realm of possibilities, pretty cool theory right?... Or nah.