|Appearance(s):||28 Days Later: The Aftermath|
|Cause of death:||Unknown; most likely starvation|
Clive and Warren were hired by an unknown company to develop an anger inhibitor which could be used to control aggressive impulses in humans.
Initially, the two used volunteers from Cambridge University, but eventually, Warren decided that they needed a test subject with extreme anger to test the inhibitor's effectiveness on, and bribed a police officer to secure a criminal from police custody in London. Clive tried to warn Warren about the danger the criminal posed, but Warren disregarded his concerns and taunted him on his lack of self-control.
The following night, Warren increased the dosage of the anger inhibitor he was giving the criminal, when he decided that the injections were too diluted. However, the criminal broke free and hit and stunned Warren, before Warren bludgeoned the criminal to death with a fire extinguisher; saving Clive's life in the process.
Warren and Clive subsequently buried the criminal's body at dawn, and as Warren contemplated to himself how he and Clive could effectively administer the inhibitor to anger patients, Clive sneezed; giving Warren the idea to use a contagion as a delivery system for the inhibitor.
The next day, Warren decided to use the Ebola Virus as the contagion delivery system for the anger inhibitor, and he and Clive then tested the inhibitor in this pathogenic form on chimpanzees. However, within the following two weeks, isolated genomes in the Ebola Virus reacted to the inhibitor and mutated; causing it to have the opposite effect, and creating a Rage Virus. When Clive snidely mocked Warren over creating the complete opposite of what the two set out to achieve, Warren attacked Clive; prompting the latter to hit Warren and quit on the spot.
The next night, Warren explained the failed result of his and Clive's experiment to his financiers over the phone, but these unknown people, however, showed interest in his creation as it had possible military applications. The phone line went dead, just as he heard noises in the lab and went to investigate. There, one of the infected chimp test subjects attacked Warren and infected him with the Rage Virus.
The infected Warren was seen the next day in Cherryl Clinton Hall, attacking a cyclist along with other infected, killing or infecting him.
Warren presumably died of starvation with the other original Infected within the following nine weeks.
Warren was radical when it came to science, and would go to great lengths to make sure the project succeeded. Warren was usually able to hide his anger under a calm demeanor, but when his work was mocked, he was prone to lashing out. However, Warren still had considerably more control over his anger than Clive.