Extremis is an advanced form of genetic manipulation created by Maya Hansen and Aldrich Killian, using nanotechnology. It grants the human body the ability to heal and regenerate from physical damages, deformities and even psychological damages. This also includes the regrowth of severed limbs in a very short timespan, various physical enhancements as well as an exothermic ability.
Extremis was created by Maya Hansen in 1999, with Tony Stark providing additional aid through a formula he deduced to help reduce the volatility while intoxicated. Maya and Aldrich Killian upgraded it thanks to Advanced Idea Mechanics providing funding for it to begin experimental testing. A.I.M. recruited amputees and other disabled people as test subjects, most notably the victims of military ops. Extremis cured their disabilities after which they were convinced to work for A.I.M. as assassins and soldiers. Near the end most if not all of the Extremis Soldiers were killed by the combined forces of Tony Stark, James Rhodes, and J.A.R.V.I.S..
Extremis was also used as the main component of the serum, designated by the clandestine organization Centipede, that combined it with Gamma Radiation, a variation of the Super Soldier Serum and technology from the Chitauri for injection, in an effort to create their own super soldiers. The Extremis component was stabilized when Centipede recruited Chan Ho Yin/Scorch. Before his death, they were able to drain some of his blood from him; the platelets in his blood prevented him from being burned by his own pyrokinesis. Mike Peterson, after recovering from being knocked out by an I.C.E.R., discovered that he was now stabilized.
Extremis enhances the user's physiology by rewriting their DNA. It harnessed bio-electricity in the body and used to activate parts of the brain that governed repair and recode it chemically. This can allow a user to hack into the basic operating system of living organisms. If the user's body chooses to accept it, the user will gain regenerative healing abilities, making them able to heal all wounds, including previously-amputated limbs or even psychological damage. When regenerating body parts, the wounds take on the appearance of burning embers while growing back the lost body part, in a matter of minutes, and cooling into regular flesh, blood, and bone. Extremis also enhances physical performance, granting superhuman strength, reflexes, and overall higher resilience.
Additionally, normal Extremis users gain the ability to generate extreme amounts of heat through a complex metabolic process, generating heat from their bodies up to several thousand degrees Celsius. Extremis users are able to consciously control the amount of heat expelled from their body, causing the area of their body generating heat to glow intensely, superheating their tissues, blood vessels and nerves, and outlining them inside the body. This effect has been shown to be unstable in the event of an Extremis overload in the body, burning the flesh and causing an explosion. Trained Extremis users can focus and conduct heat through a single area of their body such as their arms or hands, and even emit fire from their mouths, though it would seem that only the most disciplined of Extremis users can perform this feat. Certain users also demonstrated the ability to conduct heat through other objects through physical contact, allowing them to superheat targets by touching them, this being most often used on metal objects to cause them to weaken and melt.
Through a combination of superhuman strength and a focus of extreme heat conduction through their arms and hands, Extremis users can strike through and destroy a majority of metal structures on contact. Due to this, they are able to overpower and burn through the metal alloys that are used in most Iron Man armors, easily destroying many of the suits in combat.
Extremis users can be easily recognized through thermal imaging as they have a much higher heat signature. They can also be identified as their pupils glow when using their powers. Extremis does not make its users entirely invincible, as wounds like a unibeam shot through the chest will be lethal, destroying the victim's heart and therefore cutting off blood flow to the brain. When the body is regenerating, it is fragile and can be destroyed with a repulsor shot. Destroying their brains and major organs through incineration has been shown to be fatal to them.
The main weakness of Extremis is the possibility that its user's body will reject the serum upon initial injection, or that the serum may become unstable within the user if they fail to regulate their usage of it properly. Extremis users are able to consciously control the amount of heat expelled from their body, but this effect has been shown to be unstable in the event of an Extremis overload in the body and if the virus is not accepted by the body or regulated in it, the metabolic process that causes the user to generate heat, as well as the bio-electricity harnessed by Extremis, will overload, causing the user’s body to rapidly build up energy and force, causing it to explode and produce a powerful shockwave. The resulting explosion is an excess of 3,000°C and instantly vaporizes the Extremis user's body, along with anything within a certain proximity of the explosion, leaving behind shadow-like marks of objects that were vaporized, much like in nuclear explosions. Due to this, Advanced Idea Mechanics had to fake several terrorists' attacks on United States' soil to cover up the explosions caused by Extremis test subjects.
- Aldrich Killian
- Extremis Soldiers
- Jack Taggart
- Chad Davis
- David Samuels
- Drew Grey
- Pepper Potts (unwillingly and stabilised)
- Michael Peterson (through Centipede)
- Chan Ho Yin (through Centipede)
- Brian Hayward (through Centipede)
- John Garrett (through Centipede)
- Daisy Johnson (through Centipede)