Tarados was born to a spice-whore mother, and probably would have had a long and difficult life growing up in the slums of Klatooine. His Force sensitivity had been revealed when he managed to cause a young human's head to explode because they couldn't tell the difference between a Klatoonian and a Nikto. He was immediately taken into the Jedi Order on Coruscant, where he led a short and difficult life.
Tarados was a bit of a jerk, and had a hot temper that he never managed to 100% control. One time he was reading the sports pages out in the Temple courtyard, wondering how is beloved Detroit Nexus were going to win a game in his lifetime. Suddenly Obi-Wan Kenobi shouted to him from way the hell across the courtyard "Hey you, Idiot Nikto Buffoon Asshat, the Detroit Nexus are going down! YOU SUCK!" Tarados had killed for less, and not only was his heritage insulted, but so was his Jawa Football League team. Since he had caused that kid's head to explode so many years ago and was then rewarded by being rescued from a life of abuse and drug addiction, he logically assumed that if he could kill Obi-Wan, well, they'd probably put him on the damned Jedi Council.
Plot to Kill Obi-Wan
Tarados had to plan carefully. He wanted to kill Obi-Wan, but he couldn't just stab him in the Temple bathroom, because there was no honor in that. His opportunity came when the bastard was captured on Geonosis, and Mace Windu recruited all the available Jedi to make a rescue. Tarados had an elaborate scheme in which he was going to be the one to rescue Obi-Wan himself to get the glory and the promotion, and then kill him when everyone was drunk.
As the Jedi infiltrated the huge Geonosian colliseum, Tarados was again reminded of Obi-Wan's slight on his JFL team. As soon as the battle was underway, he headed straight for the center of the arena where Obi-Wan was held. He noticed a bunch of animals running around...including a Nexu! Sweet mother, he thought! He could rescue Kenobi, and then "accidentally" push him right into the beast's toothy jaw. Before he could get any closer, however, he saw that idiot Anakin Skywalker's girlfriend (yes, he knew) escape her chains, and start a chain reaction that got Kenobi loose. While Tarados was occupied by battle droids blocking his path to Kenobi, he noticed that Pade and Anakin teamed up to kill the Nexu. The plan was unravelling.
Shortly thereafter, the battle was over, and there were only a few Jedi left, completely surrounded by battle droids. Tarados figured they were all going to die, so he inched his way back towards Obi-Wan, whose attention was occupied by Pade's shredded outfit, and was about to stab him. Despite the allure of Pade's backside, Kenobi sensed the dark thoughts of his fellow Jedi, and noticed his sneak attack. Before he could react, Yoda showed up out of nowhere with a bunch of gunships to rescue them. As the Jedi scrambled to get on board, Tarados lost track of Obi-Wan, and ended up on a different gunship.
Obi-Wan used a quick flick of his Jedi powers to deflect a blaster bolt and damaged the defense systems on Tarados' gunship. Shortly after the fleet departed the arena and headed for battle, Tarados's gunship was destroyed when a Geonosian bird hit the windshield. Obi-Wan was briefly upset because Eeth Koth and Sora Bulq were also on that same ship, but in the end, he was content tha he had killed his would-be assassin.