Guy Pearce's Aldrich Killian undergoes a transformation
As the creator of the "Extremis" virus, which gives anyone infected with it superhuman abilities, brilliant scientist Aldrich Killian becomes a very different person over the course of the film after testing the virus out on himself. Said Pearce of working out the character's back-story prior to shooting:
"We just sort of talked about the development of the company that [Aldrich] had begun...and the effects that Extremis had sort of had over that period of time. And you know, [in the movie] we see a couple of clips, obviously, when Tony’s in the television van and he’s seeing sort of moments of Killian, you know, in front of his people, sort of talking to his team, and you sort of see slightly different looks. And you know, you see the kind of progression of his - his look, I guess."