Sylvester "Sly" Rax, codenamed Stiletto, is a member of V.E.N.O.M.. He pilots the Piranha vehicle and wears the "Stiletto" Mask. A former street magician, Sly sees himself as a suave ladies' man, but is really nothing more than a self-centered narcissist with cheap tricks. While some would write him off for these qualities, Miles Mayhem sees the benefits someone like Rax can bring to that table. Sly also has a thing for Gloria Baker.
As a teenager, Sylvester "Sly" Rax was a street magician, using his tricks to take hundreds, even thousands of dollars from his marks... until the day he tried to pull this on a military police officer. Sly had two options: enlist in military intelligence, or be sent to jail. He chose the former, but was later dishonorably discharged due to his lack of respect for authority. However, shortly afterwards he was approached with an offer from General Miles "Mayhem" Manheim.
Mayhem recruited Rax for Project Spectrum. After their first meeting with General Manheim, he tried to hit on Gloria Baker, using a sleight-of-hand trick to steal her ID badge. Gloria was less than impressed and demanded it back. Rax was present for the first test of the Project Spectrum vehicles, and was one of the recruits to not be shaken seeing William Evans and Marcia Watkins die.
Rax was later given the opportunity to test out Project Spectrum's specialized Masks, selecting the "Stiletto" Mask for himself. Once again trying to impress Gloria with the Mask, he accidentally activated Stiletto's weaponry, firing a harpoon at her. Baker caught it and threw it back at him. Before Sly could get skewered because of his own stupidity, however, Matt Trakker used his "Spectrum" Mask to destroy the harpoon.
Despite these errors, Rax impressed Manheim enough that he decided to add the con artist to his black ops team.
Rax was part of M.A.S.K.'s first mission to neutralize the Autobots Kup and Aileron in Greece, where he rode in on the Piranha. After being captured and brought to G.I. Joe's Governor's Island headquarters by Miles Mayhem, Kup tried to persuade Rax and Vanessa Warfield let him go. Rax complained that the Autobot wouldn't shut up, but Vanessa was able to convince Kup to share his intel on the Ore-13 deposit in Monument Valley. When Kup realized he'd been tricked, Rax laughed at the fact that the Transformer thought they were going to help him. When the current Action Man Ian Noble breached Governor's Island's defenses, Mayhem told Sly and Vanessa to ensure their attacker did not find their Cybertronian assets. The two attacked Ian, but he was able to reach cover in the same room Kup was in. Action Man and the Autobot then teamed up and blew a hole in the building, only to be cornered by the rest of the G.I. Joe forces. When confronted about Kup's presence by Mainframe and Helix, Rax lied and said Scarlett knew about him. After Kup and Ian escaped, Mayhem expressed that their hand may be played to its limit, ordering Sly and Vanessa to pack their things.
Rax joined his fellow M.A.S.K. operatives in their assault on Autobot City. He was quickly knocked out of his Piranha by Arcee after M.A.S.K. and the Dire Wraiths breached Autobot City's defenses. After the Dire Wraith-empowered Baron Karza began to wreak havoc on all sides, Rax grumbled to Mayhem that he thought Mayhem had a plan. Rax, along with Vanessa and Bruno Sheppard, disappeared during the battle and was presumed dead in the Ore-13 explosion.
In actuality, however, Rax was alive, along with the other presumed-dead M.A.S.K. agents, as part of Mayhem's new V.E.N.O.M. unit. V.E.N.O.M. attacked the reaming M.A.S.K. team at Harrison's Cave in Barbados, with Sly gravely injuring Brad Turner with his Stiletto Mask's harpoons. When V.E.N.O.M. unmasked themselves to their former comrades, Sly proceeded to once more hit on Gloria. After M.A.S.K. escaped from the cave, Rax pursued Gloria's Shark in Piranha, trying to prevent her from reaching the water. He was halted by an air assault from the Thunderhawk, and Rax quickly returned fire from the ground using Stiletto.