Percival Tachyon is first featured in the series in Ratchet and Clank Future: Tools of Destruction, where he acts as the main villain in the story. As the story unfolds, Tachyon's involvment not only reveals his own history, but also information about Ratchet's past. Tachyon is the last known living Cragmite and declares himself as Emperor over his race. To compensate for his relatively small stature, he travels from place to place using a throne on top of four stilts, which also act as legs. It also has various weapons and gadgets built into the chair for when combat situations arise.
Tachyon tells of how he was an orphan, raised by Lombaxes on the planet of Fastoon. He later turned against all Lombaxes after finding out they played a part in the destruction of all other Cragmites and that he only survived as a frozen egg. He then hatched a plan to trick the Lombaxes to giving him their secrets and technology to create new things that can help the galaxy. Kaden, Ratchet's father, didn't really believe he was telling the truth, but Alister Azimuth was convinced that it was the right thing to do for the galaxy, so he granted Tachyon full access to their technology, all of their secrets. When Tachyon was finished, he had a new army, and all new technology that was more advanced then the Lombaxes'. Tachyon attacked the Lombaxes and attempted to destroy every last one even. The Lombaxes, who gave most of their technology to Tachyon, hid in the Court of Azimuth, and opened a portal to another dimension using the Dimensionator. Most escaped, but two stayed behind, the keeper of the Dimensiontor, Kaden, and his infant son, Ratchet, who Kaden sent to Veldin shortly before he fought Tachyon. Kaden then returned to the Court of Azimuth, but when he got back their his partner, Ratchet's Mother, was already gone, according to Azimuth, suggesting she either went to another dimension or was killed by Tachyon's troopers.
Kaden soon left the court to finish off Tachyon. Tachyon accepted the battle and killed Kaden. He then set about making plans to find out the Lombax Secret, with the hope it will bring back all the trapped Cragmites and finish off the Lombaxes in the other dimension.
Sometime later he first meets the heroes, Ratchet and Clank, on Metropolis, attacking the city with his army of Drophyds to find the Lombax hero. After confronting him in his throne, he introduces himself "Emperor Percival Tachyon, crowned prince of the Cragmites, and ruler of the universe" but hearing his name Ratchet comments "Your names Percival" and Clank laughs. Tachyon, not amused, screams "Emperor!!!" and then says if he lets him kill him, he won't attack the city any more. Ratchet sarcastically says "Fair enough" and throws Clank over to his ship, where the Lombax then wacks the emperors throne and leaves with Clank.
Tachyon is seen on camera screens on some planets, commanding troopers, singing poems, and more. After beating one of the challenges in the Fight festival, Tachyon is seen on a screen after Captain Qwark gives Ratchet and Clank an infobot of Tachyon's full plan, telling the captain to stop messing around and finish the work he told him to do. When getting back to the ship, Ratchet and Clank then turn on the infobot, revealing a video of Tachyon explaining his plan. In the video, Tachyon also advertised for people to join his army, with the help of Qwark. After Qwark stole the Dimensionator and flew to the Cragmites homeworld, Reepor, with it, finding Qwark, Tachyon then took it. Ratchet and Clank confronted the emperor with it on Reepor, and Tachyon activates the Dimensionator while saying "its time for the Cragmites to rise again", however, when he pulled the lever, it did not work. Tachyon, puzzled that the device didn't work, tried again, but it still didn't work. Tachyon getting upset, gave it a great big pull and screamed "To Rise Again!!!" and it worked, opening a portal from the Cragmite dimension, releasing them, while laughing.
With Tachyon with the Dimensiontor, Ratchet and Clank went to Fastoon, knowing Tachyon would be there. After Ratchet battled and defeated some of Tachyon's Cragmite army, the emperor talked to the Lomabax in his ship, mocking him and his kind, and said if its answers he seeks to meet him in the Court of Azimuth. When confronted by Ratchet on Fastoon, he offers him a chance to live with other Lombaxes, in a different dimension. Ratchet refuses, realizing his friends would still be in danger and battles Tachyon in the Court of Azimuth. After half of the battle, though, Tachyon's robotic throne starts to malfuction and accidentally opens a portal to another dimension, sucking him in, but just as Ratchet & Clank though he was defeated, a leg from his throne pulled the heroes in. Ratchet and Tachyon then continue to battle on an asteroid in some type of asteroid dimension. After a long battle, Tachyon is defeated in the dimension, destroying his throne, and removing the Dimensionator from his head. Tachyon fell to the ground, and said that Ratchet couldn't kill him as only he knows his true purpose and name and that he and the Cragmites would return, and his kind would never be safe, and then gets sucked into a Black Hole, where he disappears.