It's all in the name with Vicious: he is ruthless, bloodthirsty, cunning and ambitious, willing to do anything in order to secure a position of power. He is a member of the Red Dragon Crime Syndicate in Tharsis, and is often referred to or depicted as a venomous snake. His weapon of choice is not a firearm, but a katana which he wields skillfully, even against gun-wielders. He was an infantry rifleman during the Titan War and is shown firing an automatic pistol in a Session 5 flashback, as well as in the Session 26 flashback of him and Spike fighting back-to-back. Early on, Vicious is sometimes seen with a black bird on his shoulder. This bird is eventually used as a distraction and weapon, either a cybernetic or robotic construct with built-in explosives.

Vicious was Spike's partner in the Red Dragon crime syndicate until they fell into conflict over Julia. After Spike's supposed death, Vicious also leaves the Red Dragons briefly to fight in the Titan War of 2068 although his precise motivations for enlisting are debated. The blood feud between Spike and Vicious is an ongoing storyline throughout Cowboy Bebop. Vicious believes that he is the only one who can kill, or "awaken" Spike, as Spike is the only one who can do the same for Vicious. Vicious' real age is revealed in the official guidebook The After: at 27, he's the same age as Spike, although he appears to be much older. The age 27 is a significant age in the series because of the connotations it has to some legendary musicians passing away at that age, who are called the 27 Club. He may seem older due to the heavy, ever-present bags under his eyes. Because of this and his affinity towards Red Eye deals, it is possible that he is a user of the mind and vision altering drug. Evidence of this is briefly seen during a flashback at Julia's apartment which shows a capsule of Red Eye on the window sill during Session 13: Jupiter Jazz, Part 2.