Hi-Q was a Nebulan scientist who- with his partner, Hi-Test- was tasked by their Council of Peers to find a way to prevent the Transformers were ever returning to Nebulos. He developed a bomb which unleashed a special radiation into the planet's atmosphere, rendering all their energy sources poisonous to Transformers. Unfortunately, Hi-Test became mad with jealousy over Hi-Q's accomplishment, and became determined to ruin it. To that end, he teamed up with the criminal Throttle, and stole Hi-Q's experimental Powermaster Process. Combining it with the binary-bonding procedure used to create the Headmasters and Targetmasters, Hi-Test and Throttle became the living engines- Powermasters- for two Decepticons- Dreadwind and Darkwing- which had been rendered inoperative by Hi-Q's invention.
The Decepticons ravaged the world until Goldbug and a band of Autobots arrived, seeking Hi-Q's help to rebuild Optimus Prime. Hi-Q was reluctant, as he did not consider the Transformers living beings. He did, however, warn the Autobots the tainted Nebulan fuel. The Autobots were unable to battle the Decepticons in their weakened state, and eventually, they began to die. Hi-Q was troubled by this, and agreed to rebuild Prime into a new and stronger form- even though the Nebulan energy that would revive him would also kill him. When Prime expressed his gratitude at having a few fleeting moments of true life again, Hi-Q and his research team agreed to save the Autobots by becoming Powermasters. Hi-Q bonded with Optimus Prime himself. The empowered Autobots drove the Decepticons off-planet, but Hi-Q and company chose to leave as well.
Hi-Q remained bonded to Prime for some time, until they both began to experience mysterious bursts of agonizing pain. Prime concluded that he and Hi-Q must be incompatible, and released him just prior to sacrificing his life to stop Unicron. However, Hi-Q soon realized that Prime was wrong- far from being incompatible, they were merging into one being. Exposed to nucleon, Hi-Q's transformation accelerated, resulting in Prime's spirit being housed within Hi-Q's body.
Eventually, Hi-Q and Prime were restored by the Last Autobot, who recreated them as a new Optimus Prime.