Roberts was a mercenary who worked for Ned Bolger, thinking he was Arvin Sloane.
Season 4
Roberts was assigned to fool Vaughn into believing that his father was alive, so he had Vaughn travel to a library and inject himself with an anesthetic. After Vaughn woke up a few hours later, he was approached by Roberts. He told him that his father was still alive and that if he wanted to know more, he would have to meet him again in the future (Nightingale).
Vaughn met with Roberts again over a meal at a café, where he showed photos confirming that his father was still alive and well. Vaughn accepted the information he was given and teamed up with Roberts. Roberts introduced him to three of his subordinates, Gregor, Jan, and Sabina, and informed them all of an impending heist. The team was ordered to steal an artifact from an APO convoy. Before they could, he sent Vaughn and Sabina to Bordeaux to collect a laser that would cut through the safe housing the artifact. After they stole it, the team was ready to perform the heist. However Vaughn told the team they'd do things his way so no casualties would be reported. Vaughn and the mercenaries stole the artifact, but Gregor or Jan disobeyed Vaughn and fired at the agents. Everyone except for Vaughn was slain in the firefight and Vaughn confronted Roberts, demanding to know what really happened to his father. Roberts told Vaughn that the photos were fake and his father was really dead. Once Vaughn demanded to know who Roberts worked for, he told him it was Sloane (Pandora).
Bolger detonates Roberts' elevator.
Roberts was later taken out of APO custody to identify whether or not he was working for Sloane and he told everyone that the man he worked for was Sloane, but he looked different from him somehow. Roberts was forced to call one of Sloane 2's subordinates and told him he had the artifact they needed, a transfer coil. Roberts agreed to meet with Carter at a hotel and was sent there with APO agents guarding him in disguise. Unfortunately, he met with someone else besides Carter and he told him the meeting had been moved to the top floor. While inside the elevator, Sloane 2 spotted Sydney in the adjacent hotel and activated a bomb on top of Roberts' elevator, cutting through the cable. Roberts screamed horribly as his elevator plummeted all the way to the basement floor, killing him and the accompanying terrorist instantly (Another Mister Sloane).