Reignfire was initially a test subject of Dr. Siegmund Joshua's. created with an injection of the cellular material of Roberto da Costa, former member of the New Mutants known as Sunspot. With a new genetic template to duplicate, the protoplasmic goo began to pattern itself off of the DNA sample and thus shared Sunspot's appearance and powers. Additionally, when Reignfire was within close proximity to Sunspot he could activate a telepathic link with his host and psychically imprint himself onto him, thus making Sunspot appear to be evil.
The Mutant Liberation Front (MLF) was incarcerated and left leaderless after Stryfe's body was annihilated in the timestream. Reignfire stepped in to fill this void. He liberated four members of the original MLF: Forearm, Reaper, Wildside and Tempo, and added two more to their ranks: Moonstar and Locus. He charged his team with the mission of killing Henry Peter Gyrich, a man who had stirred up public hatred & fear of mutants. However, their attempt was foiled by X-Force and during the battle the powers of Locus and Sunspot reacted together in an odd way; teleporting the pair to parts unknown. Before doing so, Reignfire said Cable's real name.
When Reignfire made his presence known, it was noticed how remarkable similar he was to Sunspot in both appearance and powers. Since at the time Sunspot was missing in action (MIA), that possibility was not ruled out by Cable. His suspicions were seemingly confirmed when in the middle of a battle Reignfire removed his mask to show that he was indeed Roberto.
Cable used his telepathic powers to forcefully remove the Reignfire persona in Sunspot, and supposedly succeeded. As an unexpected side effect, Sunspot gathered some knowledge from Cable's mind, including information about Askani, Cable's religion and language. There were occasional moments when Sunspot had a mental struggle to suppress evil urges, but for the most part all seemed well.
Later, Sunspot visited his friend and former New Mutants teammate Skids in Colorado when the pair were attacked by none other than Locus and Reignfire. Although things once more went awry with Locus' powers when they come in contact with Skids' force field, Reignfire's mission was generally a success as Sunspot was captured. Once Sunspot had been shackled to the wall Reignfire began to tell the story of his true origin; revealing he was not an evil Sunspot, which many had believed. Reignfire wanted to kill Sunspot, but failed when X-Force came to his rescue.
When Reignfire appeared next, he was back with the Celestials' ship. X-Force found the ship and the protoplasmic figure inside and after another lengthy battle Reignfire was crushed to death by a Celestial golem inside of the ship.