Tony Stark built the Extremis armor after a fight with Mallen and losing. In order to stop MAllen he took a drug called Extremis that had given Mallen his powers so he could fight him. But Tony altered the drug a little so it wouldn't kill him. And so he wouldn't have to sit in a cocoon forever. Tony fights Mallen in the end and demolishes him. Beating him to a bloody pulp, giving Mallen the warning to give up. Mallen of course decides to attack Tony choking him while he's in the armor, forcing Iron Man to blow a hole through his chest with the Uni-Beam. Then putting both hands on Mallens head and blowing it up. Tony gains the ability to control anything tech, like he can control 20 suits at once, and other things. Call people from his head, and really be a badass all around. This is just if you never found out in the one year you were waiting.

basically there was a guy named malled who got this thing from future farm labs called the extremis virus.... tony fought him and basically got demolished so he took the extremis virus himself to beat him.... the extremis basically connected him to the armor, he could think about the armor and it would come flying onto him... pretty awesome huh?

Try the video's page, some Iron Man videos on the subject up there.