- "A ravenous beast. The same blood runs through both of us. The blood of a beast who wanders, hunting for the blood of others."
- ―Vicious to Spike[src]
Vicious was born in 2044. Much about his early life is unknown, but at some point in time, Vicious develops a relationship with Julia and meets Spike Spiegel. Spike takes Vicious under his wing inside the Red Dragon Syndicate. Under Spike and Mao Yenrai, Vicious rises up the ranks inside the Syndicate. It is unclear when and why Vicious fights in the War on Titan, but after the War, he testifies against Gren for being a spy. 
Vicious gradually lost respect for Mao, and, when Mao intended to sign a truce with Carlos of the White Tiger crime syndicate, decided to take action. He sabotaged Carlos' ship when he visited Mao's headquarters to explode on his return trip. His men waited until Mao watched Carlos' ship explode to burst in and kill Mao's men. Vicious himself killed Mao, but not before smiling when Mao said he would never have done this if Spike were still there.
Vicious knew that Spike would be after him and decided to trap Faye Valentine who would be looking for Mao's bounty. Allowing Faye to contact Spike to tell him where she is, Vicious waited in a cathedral with his men. He watched Spike arrive and kill most of his men before advancing to him on the second floor. They fought, each wounding the other but Vicious was able to push Spike through a window. However, he saw Spike left a grenade and ran, surviving. 
Vicious received a request to sell Red Eye from someone named Julia on Callisto. While it was unusual for someone to do that directly to him, The Van allowed it, sending Lin with him. Vicious and Lin went to the moon to meet the person. They first saw Spike, who was also drawn to the communication. Lin saved Vicious by standing in front of him and shooting Spike, allowing them to escape.  Later, they were contacted by the seller and Vicious directed the person to the top of a skyscraper. The deal was going according to plan until the person revealed himself to be Gren. Vicious coldly answered his question of why he testified against him three years ago with the simple claim that there is nothing to believe in, including camaraderie. Vicious escaped the explosion hidden in his suitcase with the payment and was saved by Lin again when he took a bullet for him. Vicious left him there, took the Red Eye, and escaped, firing on Gren's ship and Spike's, which had just arrived. The bag of Red Eye exploded, forcing him to retreat to the syndicate ship. 
Eventually, Vicious finally made his move on the Van, taking a team to storm the Van's chamber. The Van were ready, having been tipped off by a fortune teller (or so Wang Long said). They imprisoned Vicious and sent teams to kill Julia and Spike. When the Van decided to execute him, they were surprised to see that Vicious' men turned on them, freeing Vicious and killing the others. Vicious killed Wang and declared himself the leader of the syndicate. Learning of a relationship between Spike and Julia, Vicious tells Julia that if she doesn't kill Spike that he will kill them both. After Spike and Julia both disappear Vicious hunts for them as he continues to rise in power inside the Red Dragon Syndicate. 
Vicious is a tall and thin man with gray, untamed hair. His weapon of choice is a katana. This gives him a slight resemblance to Goemon Ishikawa from Lupin III, just as Spike seems to be a homage to Lupin himself and Jet's beard and preference for firearms invokes Daisuke Jigen. He is usually seen with his pet cormorant perched on his shoulder and his katana in hand. Vicious is 27 years old, though appears older due to his grey hair, the deep bags beneath his eyes, and a generally worn face. His elderly appearance at his young age could possibly be attributed to the events on Titan, some event linked to it, or his implied Red Eye addiction. He usually appears with a scowl, although there are a few scenes in which he smiles albeit sadistically due to his nature.
Vicious is portrayed as a cold, sadistic, ruthless, bloodthirsty and ambitious man who prefers solitude over company. Within the Red Dragon, he is feared by his senior leaders, the Van, precisely because of his social climbing, and is willing to do anything to get what he wants, and doesn't place the slightest moral scruple in fulfilling heinous acts to reach his goals and achieve a more powerful position. Furthermore, he ruthlessly sacrifices his subordinates and conspires behind those who have sworn allegiance.
He is perceived by many people to be the dark half of Spike, basically showing the same indifferent attitude towards everything, although more sociopathically and less passive. He also shares with Spike a strong cynicism and rather similar opinions on life and several ethical issues.
Vicious doesn't show the least respect for traditions or ancestors and, proof of this, considers the Van's code, the doctrine of honor of the Red Dragon Crime Syndicate, a bunch of unfounded principles, principles that he usually transgresses, and begins a crusade in order to destroy them. He also doesn't show any respect for the Van, considering them incompetent old corpses lost in their past, nor for any human life.
Curiously, Vicious is never seen smiling during the whole series, apart from the sadistic grin during battles and the smirk in flashbacks showing him fighting alongside Spike.
Given the conditions of his conjunctiva, it is quite credible that Vicious uses the drug Red Eye.
Because of his slimy and often ambiguous nature, the Van terms him as "the poisonous snake," or, more simply, "the snake." This epithet is also given to him by the shaman Laughing Bull.
( ) = Speech of other characters
- Vicious talking to Spike in Session 05: Ballad Of Fallen Angels.
"When Angels are thrown out from Heaven, they become Devils; you agree, don't you, Spike?"
"You should see yourself. Do you have any idea what you look like right at this moment, Spike? ("What?") A ravenous beast. The same blood runs through both of us, the blood of a beast that wanders, hunting for the blood of others. ("I've bled all that kind of blood away.") Then why are you STILL ALIVE?!"
- Vicious to Spike in Session 13: Jupiter Jazz (Part II)'
"There is nothing to believe in. There is no need to believe."
"Make your move."
"I'm the only one who can keep you alive. And I'm the only one who can kill you."
- Vicious to The Van in Session 25: The Real Folk Blues (Part I)
"And you will shed tears of scarlet" (English) "You shall shed red tears" (Japanese)
- Vicious to Spike in Session 26: The Real Folk Blues (Part II)
("Julia passed away. Let's end it all!") "If that's your wish."
Vicious does not show much character development throughout the series, as his initial attitude and beliefs remain constant until his last appearance. While his character does not develop internally, more of his life story is revealed, such as his involvement on Titan. Also, his relationships with other characters become more apparent, including his relationships with Spike and Julia, suggesting a love triangle.
- Vicious appears in every episode in which Julia is mentioned.
- Vicious's bird is a homage to Captain Harlock's bird from Endless Odyssey. Also, in the last episode of Space Dandy, you can see a bird that looks like Vicious's bird.