before February 2009Edit
O'Neil grew up in Fresno, California. His famiy was poor, and his father worked as a criminal. He made friends with Oli Struth, a weak-willed son of a jeweler, and could effectively persuade Oli to do whatever he wanted.
O'Neil obtained a full-ride college scholarship from a company called W-Y, and attended UC3R. On his first day of school, he strong-armed his way into the Crazy Shoes, after a tense standoff against gang leader Garvin.
Later that day, he was rejected from Sigma Sampi Omicron, and vowed vengeance on the fraternity. He also learned about Dragonstorm, and became motivated to join the club. However, Dragonstorm wanted nothing to do with him, and even threatened to kill him unless he left them alone. This just made O'Neil more motivated.
During a gang fight, he killed Garvin and assumed command of the Crazy Shoes. He then made alliances with with other gangs, starting with rival gang the Mauve Shirts, led by Foley. In this way, he built himself a small gang empire.
He also worked for the school newspaper, the Three Rivers Tributary, as an investigative journalist. His goal, however, was to kick editor-in-chief Gregory Cass out of his position so that the newspaper would stop looking over Dragonstorm's shoulder.
After shutting down Sigma Sampi Omicron due to their illegal file-sharing network, O'Neil reserved their old headquarters for Dragonstorm. He also orchestrated a plot that ended in the deaths of Gregory, the Mauve Shirts, and all the Crazy Shoes (except Julian), but impressed Dragonstorm enough that they allowed him to join. (Nietzsche's Soldiers 3')
After college, O'Neil got a job at Pelvanida, just like the other high-ranking members of Dragonstorm.
In 2004, he worked on a project with Zachary Johnson to create a strength serum for equestrians, but later stole the unfinished prototype. There are indications that he used the serum on himself.
During the terrorist invasion, Keegan joined a team composed of himself, Pietr Kozlov, Lester Montgomery, and Howard Hicks, who were trying to search throughout the base and locate Dr. James Zanasiu, a scientist who had found a top-secret Dragonstorm disc. During a shootout in Yuri Kerzach's office, the rest of his team was captured, but O'Neil escaped. He returned to a hidden lab behind the freezers and informed Calchas that the others had been captured.
Later he sneaked into the kitchen when James' team was searching it, and locked James in the freezer. However, while attempting to escape the kitchen, he was captured by Neville Ivers, Sharon Varma, and Zachary Johnson. When terrorists attacked the group, O'Neil temporarily sided with the heroes in the ensuing shootout, and escaped during a powerout. He was still in the laboratory when the fire system was activated and everyone in the lab passed out. (Darwin's Soldiers)
before July 2009=Edit
O'Neil survived the terrorist incident. Afterward, he and Dragonstorm consolidated their power over the facility by firing many personnel who weren't allied with them, and building a secret new lab that only people with ultra-high (Dragonstorm) clearance could enter.
During James' team's invasion of Pelvanida, O'Neil entered the cafeteria at the same time Rudyard Shelton and Dr. Zanasiu was hiding in there. Wayne Anthony, who was working as a server at the time, hid Shelton under his salad bar even as O'Neil ordered a salad from him.
Later, as Lab 101 fled the base in a convoy, O'Neil noticed somebody (Shelton) sneaking around in the machinery surrounding the lab. He chased the person onto the roof, but then was knocked out by a flashlight-whip to the head. He didn't get a good look of the person, only knew that they were male and human. (Survival of the Fittest)
before September 2009Edit
O'Neil was sure that the man who attacked him was still hiding within Dragonstorm's ranks, and searched for him even after the convoy had safely escaped Nevada. He used Darien Walters as an assistant; since Walters had been driving Lab 101, he was one of the few who could be trusted.
O'Neil was knocked out along with everyone else in Lab 101 during Bruce Tinner's thought chip experiment. He later spoke during the funeral for Alpha Leader, Beta Leader, Gamma Leader, and Dr. Tinner. (Nietzsche's Soldiers)
O'Neil escaped Lab 101 in the convoy after James' team destroyed it, and assumed joint command of Idaho Prison Base along with Julia Race. While there, he awarded Special Commendations for Bravery Under Fire to Walters, Achates, Achilles, and Rucker Jamesson. He transferred to New Peenemunde Harbor before Idaho Prison Base was destroyed. When Soundwave took over the facility, he escaped with Trinity to the Washington, DC base. He also informed Dr. Johnson Zenarchis of the situation at New Peenemunde.
- O'Neil's surname originally fluctuated between being spelled 'O'Neil' and 'O'Neill', before Serris finally declared that O'Neil was the canon spelling. After the first role-pay, the correct spelling became standard.
- Despite his death ni Disruptive Selection, Zachary Johnson mentions visiting his trial during the aftermath of the Dragonstorm incident.