From the anime guides and some brief flashbacks in a couple of episodes, we know that he and Spike worked together in the Red Dragon syndicate before Spike faked his death. They were described as partners. We know that Vicious was in love with Julia – she was his woman until she and Spike fell in love.
We know from Jupiter Jazz that Vicious did a stint in the military fighting a war on Titan, serving with Gren.
In Jupiter Jazz, Vicious was described by the syndicate’s elders as having a heart colder than (a perpetually cold) Callisto. Indeed, watching him in Ballad of Fallen Angels, Jupiter Jazz 1 and 2 and Real Folk Blues 1 and 2, he is certainly cold. Very full of hate, especially hatred for Spike.
There WAS a bit of humanity seen in Vicious in Jupiter Jazz part 2. Gren is telling Faye how he knew Vicious. They were comrades in the war on Titan, being in the same unit. Flashback showed Gren spotting Vicious sitting with a little wind up music player with a look on his face that I can only desribe as ‘longing’:
Gren walks over and sits beside him saying it’s a lovely song, and he’d like to play it on his sax when he gets back from the war. He asks what it’s called, and Vicious only says “Julia.” I heard a longing in his voice, it was almost wistful. He then gives the music box to Gren so he can learn it to play on his sax.
He WAS cold. He got wind of Spike’s plan to leave the syndicate and his plan to run off with Julia and confronted her before she was able to meet with him. His plan was for her to kill him “He dies or you both die” he told her. Julia didn’t go through with it and instead went into hiding, leaving Spike to think she had abandoned him.
Vicious appeared to be motivated by hate and rage. But there was love there. One has to speculate what it would have been like to be loved by such a personality.
There is a scene in Jupiter Jazz part 2 where Gren confronts Vicious about the transmitter found in the music box he had given him. His reaction spoke volumes when Gren told him that it was Julia who suspected the transmitter when she found out that it came from Vicious.
Julia was hunted, but it was by Vicious. He wanted her back in the worst way. We find out in Real Folk Blues part 1 when she’s warned by Shin that it wasn’t safe that she was on the run.
When they finally meet for the last time in Real Folk Blues part 2, Vicious and Spike are fighting to the death, each intent on killing the other. They were very evenly matched and it was a draw until their weapons get reversed. They have possession of each other’s weapons when Spike tells Vicious that Julia was dead.
They clash once again and Vicious strikes the floor instead of Spike, giving Spike the chance to shoot him dead, essentially committing suicide by ex partner. Edited 14-Apr – Vicious was charging Spike dragging the blade on the floor, not hitting the floor instead of Spike, which is how it looked to me the first several times I watched the ep.
Much is made on the internet that Spike couldn’t live without Julia. There is no evidence to support this in the series. He loved her, she was his soulmate, the other half of himself that he longed for. She is the first woman he had met who he felt was truly alive and gave him an appreciation for his own life (Real Folk Blues part 2 and Cowboy Bebop the movie).
I submit that it was Vicious who couldn’t live without Julia, not Spike. We don’t know what he was like before she left Vicious for Spike, but it looked like something inside him died, if it was ever alive to begin with. He fought savagely until Spike told him she was dead.
He had one last chance to kill Spike and instead decides to strike the floor instead of Spike. Without Julia, he had no reason to live. He was so cold and hateful, and with the little on screen about him, it may be safe to say nobody loved him. Lin goes with him in Jupiter Jazz not to protect Vicious but to “protect the rules” because the elders ordered him to. Vicious, judging by what’s on screen, was very much alone.
Spike lived for at least three years without Julia, thinking she had abandoned him. He really had little to no hope of ever seeing her again, perhaps thinking she had chosen Vicious instead. He learned part of the truth from Gren in Jupiter Jazz. Spike had a new life and had made a strong connection with Jet. He had someone who loved him and took care of him. He loved Jet and in turn took care of him too. He was passionately interested in Julia, what happened to her and why she didn’t meet him to run away with him, but ultimately, he was surviving. I believe Vicious didn’t have that connection with anyone else, and when he found that the only person he loved was dead,
he decided that he didn’t want to live and allowed Spike to kill him.