In 1998, Steve Burnside was captured by Umbrella along with his father, one of the company's lesser employees who had attempted to sell off company secrets to rival organizations. Steve's mother was murdered by Umbrella's agents while he and his father were imprisoned within the company's secret prison facility on Rockfort Island.
Steve's term at Rockfort wasn't as indefinite as Umbrella had intended; the island was attacked by an unknown paramilitary force and the bombing resulted in the T-virus escaping from the lab complex, infecting most of the staff and prisoners. Steve managed to escape in the confusion and shortly afterwards he encountered (at gunpoint) Claire Redfield, Umbrella's latest prisoner. Since Claire wasn't affiliated with Umbrella and was only interested in getting off the island alive, Steve decided to stick with her until they managed to escape. Together they fought through hordes of zombies, B.O.W.'s and other mutant creatures, outwitted the island's insane director Alfred Ashford and survived the numerous death traps he had prepared for them. During the pair's struggle, Steve was also forced to kill his father who had turned into a zombie.
After Steve and Claire managed to escape Rockfort, the plane they had commandeered was remotely hijacked by Alfred, who forced them to land at the Umbrella Antarctic Base. The horror of the T-virus had been unleashed there as well, and not only that, but Alfred's sister Alexia - who had been sealed away in the facility's lab for fifteen years - had awoken from her cryogenic sleep after her own creation, the T-Veronica virus, had fully bonded with her body. The mutant Alexia captured both Claire and Steve, taking the latter to her hidden dungeon where she decided to experiment on him, injecting him with the T-Veronica virus. When Claire was later freed by her brother Chris, she ran to find Steve and was horrified to see him mutate before her eyes.
After transforming into a hulking monster, Steve attacked Claire whilst wielding a giant axe. He chased her down until she locked herself inside a dungeon cell, but Alexia manipulated one of her many pod-tentacles into breaking through the wall and restraining Claire. Steve broke in and was about to deliver the killing blow to Claire when his own consciousness seemed to re-emerge, his mind fighting to resist the violent urges brought on by the virus. He brought his axe down upon Alexia's tentacle, freeing Claire, but the remainder of the limb stabbed Steve in the stomach and smashed him into the wall.
While dying, Steve quickly reverts back to normal and tells Claire that Chris kept his promise and that he loved her, but was unable to fight any more. He succumbs to his injuries. He was only 17 at the time of his death. After his death, his body was recovered by the HCF, a private paramilitary group commanded by Albert Wesker. Wesker wanted the T-Veronica virus lingering in Steve's body to further his own goals, and years later would offer up the virus to South American drug lord Javier Hidalgo in exchange for a stake in his operation.
Steve was only seventeen years old when he was imprisoned by Umbrella. As with most teenagers, he was headstrong and impulsive; he tried to put on a tough act around Claire when he met her, but he was merely attempting to hide the anger and bitterness he held toward his father, whom he blamed for his whole situation. While teamed up with Claire, Steve develops a bond with her and even falls in love with her, which he admits to moments before his death.
MutationEditAfter being injected with the T-Veronica virus, Steve mutated into a hulking, green-skinned monster; his size increased dramatically with his back enlarging into an unsightly hump, with the skin tearing in places and long boney spikes erupting on one side. The only part of his body that still resembled a human was his head which, aside from the skin, eye and hair colour, hadn't changed.
Steve possessed immense strength in this form, capable of lifting and throwing large, heavy objects that normal humans could not. He wielded a gigantic axe and attacked Claire with it.
The virus warped Steve's mind as well as his body, driving him into a violent frenzy. It is possible that the virus made him susceptible to mental control by Alexia, but this has not been confirmed. However, Steve possessed an extremely strong will and was able to resist the urges brought on by the virus. After being fatally wounded by Alexia's tentacle, his body returned to normal.