Many years before the war, First Officer Ratchet was a member of the Science Division on Cybertron. He was there when Ironhide of the Defense Force, looking over his shoulder, visited the Science Division. Ratchet used to be a politician, Optimus Prime's chief liaison to the High Council of Ancients. He tried to find a peaceful solution to the civil war, and when this failed, he became a battlefield medic.
Later, he greeted Commander Starscream when the latter returned from a patrol in the Eshems Nebula and repaired his wounds. When he reported of promising findings in the archaeological site near the temple of Simfur, Starscream was somewhat dismissive of the science division's efforts in light of their previous failures. Later, at the excavation site, Jazz tweaked Ratchet by asking if the artifacts found were as old as the first officer. Ratchet exaggerated being upset and deployed his various tools, threatening Jazz that he was just as good as disabling vocal processors as he was fixing them. When Optimus walked off with Protector Megatron, Ratchet whacked Jazz on the back of the head. He was present when Arcee's team found a strange artifact with the strange symbol and helped escort the relic out of the dig site when the aliens whom Starscream had encountered earlier suddenly attacked the planet.
After the alien attack ceased, Ratchet and Arcee analysed the remains of the attackers at a laboratory in Burthov, discovering that the aliens were similar in structures to Cybertronians, even to the point of having something similar to a spark core, but only lacked the means to transform. Before they could speculate further, Signal Flare arrived, with orders from Optimus to assemble for a meeting immediately. At the gathering, Optimus explained how Megatron was demanding they betray their principals of pacifism to go to war with the aliens, and while he implored to the members of his science division to not leave with the army, he also said they could freely choose to go without fear of reprimand. Naturally, Ratchet stayed on Optimus' side.
Hoping to learn some answers about the mysterious relic, Ratchet, Elita-Oneand Arcee took most of the recovered fragments found at the dig site to the lab for immediate examination. After Optimus Prime, Jazz and Prowl broke into Megatron's quarters to get a close look at the intact relic, Ratchet was surprised to learn that the ancient monolith seemed to be in better than had found it in. An unexpected shock same when analysis of the fragments detected the same symbol in the same area on all the different pieces, and what's more, the symbol was also on Optimus's head. Ratchet claimed that this was proof that the Dynasty of Primes existed, and that Optimus was linked to them. Later, at a dig site near Burthov, Ratchet bestowed the name Optimus Prime on his leader, with the opinion that it had a nice ring to it, though Optimus himself thought it might mean "records clerk" for all they knew. Examining the ruins, Optimus wondered aloud why only the relic Megatron possessed remained intact, leading Ratchet to hypothesis that the others had been smashed deliberately. Further speculation was halted by Prowl's security detachment, who had orders to arrest Optimus on flimsy charges of treason. As they were being led away, what no one in the group realised was Megatron had marked all but Optimus for death. Ratchet assisted in the recovery of Prowl when Brawl fired an explosive shell into the convoy. As the group made a run for Burthov, Optimus Prime personally took care of Starscream's group.
Shortly after Optimus took on the mantle of a Prime, he and Sentinel Prime stood before his followers, which included Ratchet. After those following Optimus Prime were declared traitors, the planet erupted into civil war.
During the war, Optimus Prime decided to launch the AllSpark into space to keep it out of Lord Megatron's hands. Bumblebee's team was successful in diverting the Decepticon leader's attention at Tyger Pax, but the young Autobot was grievously injured as a result. As he was carried away on a stretcher, Ratchet declared Bumblebee a hero for delaying Megatron long enough for their plan to work. Ratchet repaired his body, but contrary to what he told Jazz years earlier, was unable to repair Bumblebee's vocal processor.