Extremis (Earth-199999)

Extremis is a chemical substance synthesized by Maya Hansen that allows for various genetic manipulations in the human body. It is notably capable of regrowing lost limbs and curing disabilities. However, it is also prone to "glitches," in Hansen's terms, leading to violent explosions in some subjects and above safe dosage amounts. Hansen sold Extremis to the think tank A.I.M., led by Aldrich Killian, who exploited its violent potential to create superpowered soldiers. These soldiers were granted extreme thermal powers, able to melt through powerful metal at a touch—Killian himself was even able to breathe fire. Killian even weaponized the consequences of Extremis' "overdose," coercing soldiers to detonate themselves in public spaces. Killian's goal of fueling the war on terror with these soldiers was stopped by Iron Man, James Rhodes, and Pepper Potts in December 2012, and Stark found a way to reverse its effects on the body. Over the following year, Extremis mysteriously found its way into Project Centipede, an initiative designed by an unknown party to manually "create" superheroes using various materials from the past known to do so. Its explosive quality remained, and Michael Peterson nearly lost his life to it save for the intervention of S.H.I.E.L.D., who cured him of the Centipede concoction in his body.