I started this thread a long time ago and it has disappeared off the forum. At the time, posters were sure extremis had no part in Tony's personality, because they thought Extremis was pre-CW.
Now that IM 12 is out, It has become clear that Extremis is very much a part of Tony Starks makeup, because he still contains those pesky, little, nanites after IM 12.
So, Iron Man's behavior in Civil War is affected by Extremis. I, personally hadn't specifically, seen the Extremis effect in Starks personality, being under the impression that he would be rid of extremis, in some way, at about issue 12 of IM. However, in light of this new revelation, I am now open to judging Tony a little more harshly. I am now thinking that Tony's viscious attack on Cap is the extremis brutality. And also the spray he gave Jessica Drew, in NA.
What I can't reconcile, is that in IM 12, Tony sacrificed his life to save Steve Rodgers. If Tony is a loose cannon, compliments of the extremis virus, maybe he has learnt to control his extremism during the last story arc of Iron Man, and what we are actually seeing is not the extremis Tony Stark, but a post-extremis Tony Stark.