Warren is a close accomplice to Mr X in the Streets of Rage series. He joined the crime lord on the Princess Grace and presumably helped him to plant the two bombs. As Mr X attempted to escape, Warren was ordered to deal with the threat of Axel Stone, Blaze Fielding and Max Hatchet, but was kicked in the face by Axel.
It is unknown what happened to Warren after the brief scuffle; he could have been killed by Axel's kick or by the explosion, or maybe even survived the blast. Either way, Warren has never been seen again.