Speaking with SFX Magazine, director Shane Black explained precisely how the Extremis virus will translate on-screen, both visually and scientifically.
“In the Extremis comic book, there’s a type of thing that takes over and basically upgrades DNA. Sometimes you die. But if you live through the experience then you come out this changed thing. But the way they do it is the guy that does it is not some man chosen to be the super soldier -he’s just a militia guy.
There’s an element of realism to it as well. So what we’ve tried to do is take this very science-fictiony concept of super people, and ground it in the type of people who volunteer for this being not necessarily super villains, but just people who upgrade.I love the idea of a super villain that doesn’t wear a cape, that doesn’t wear a super suit. That goes around dressed as you are right now.
As for the science of it, once again we’ve gone back to the comic books, and I think pretty much lifted the Maya Hensen idea, that she met [Tony] long ago and had the germ of an idea, which now has come to fruition full circle, but she’s afraid because it’s gotten out there. And we go from there.
I think you’ll be interested in the effect that we generate to demonstrate what Extremis does to a human being.What we do keep from the comic is the idea that there’s a slot in the brain that seems to have been dormant, but exists in human beings, almost as though it’s waiting for human beings to find a way to fill it.”