Originally, Reignfire was nothing more than a protoplasmic entity with no real form, held in possession by the Celestials. An External named Gideon had been studying and experimenting on a mutant named Sunspot, having taken a sample of his blood and injecting it into the container holding the protoplasmic goo. Gideon titled the experiment Project: 19. The protoplasmic goo now having DNA to duplicate and build on, it patterned itself after Sunspot in both power and appearance. A bonus ability to this new creation was if it was close enough it could create a telepathic link with it's host and even imprint itself onto Sunspot's mind. This explained why Roberto appeared evil on occasion.
After the X-Cutioner's Song story arc, the Mutant Liberation Front had been incarcerated and left leaderless, until Reignfire appeared and assumed control. He liberated four of the original M.LF. members, Reaper, Tempo, Wildside, and Forearm. He then brought on Moonstar and Locus. He then ordered his team to kill Henry Peter Gyrich. They were stopped by X-Force and during the battle the powers of Sunspot and Locus clashed, causing them to be teleported away. Reignfire claimed that he was the real Sunspot. At this time, Reignfire says Cable's real name.
When X-Force encountered Reignfire again, Cable used is telepathy to separate Reignfires mind from Sunspot's. A side effect of Cable's decision was that for a period of time afterward, Sunspot had collected knowledge from Cable's mind about the Askani. Cable found out that Reignfire had linked with Roberto's mind and switched places with him, then making X-Force believe that he was the original and Sunspot was his evil counterpart. In the end Cable freed Sunspot's mind, but Reignfire still retained all of Sunspot's memories and powers.
When Sunspot went to Colorado to see his former teammate of the New Mutants, Skid, they were attacked by Reignfire and Locus. Sunspot was captured, and while shackled down Reignfire revealed his origins. Reignfire would then try to siphon all of Sunspots's powers and kill him, but he failed when X-Force came to Sunspot's rescue. Reignfire's physical form was destroyed by a molecular disruptor, he then took control of Sunspot's body, Sunspot would soon gain control and use the molecular disruptor to strip Reignfire of all his powers.
Reignfire was reduced back to it's protoplasmic form and crushed by a Celestial golem, on the Celestial's ship.