First Aid is the member of the emergency Autobots called Protectobots. He became the medical doctor of the Autobots after Ratchet passed away. He transforms into a Toyota Hiace ambulance and forms the left arm of Defensor. First Aid hates to see any machine, whether living or non-living, suffer even the slightest, and is devoted to helping and saving lives of humans and Autobots alike.
First Aid is an devoted pacifist. When the Insecticons attacked an inhabited city on Earth, Optimus Prime called upon the Protectobots to evacuate the civilians caught in the crossfire. First Aid helped an injured man discovered by Streetwise. Later, as Earth's orbit was diverted to the Sun by the Combaticons, First Aid brought civilians to a meat locker that Groove and Streetwise had commandeered to help the humans cool down.
First Aid, as part of Defensor, was the arm that wielded the rifle which totally blew up Bruticus. Afterwards, he was with the Protectobots when they saved some window-washers from a burning skyscraper. Later still, First Aid and the other Protectobots were ordered to help defend Autobot Headquarters from a Decepticon attack. They merged into Defensor and activated his useless force field, which almost immediately deactivated, allowing the Decepticons to blast Defensor back into his component parts.
First Aid's most prominent role was in the episode "The Ultimate Weapon". In that episode, he and the Protectobots stop violence among humans in the Netherlands, and the Autobots join them in battling the Decepticons. He later returned to Metroplex with an injured Blades to repair him. It turned out the Decepticon attack was a diversion for the Combaticon Swindle to infiltrate Metroplex and steal his transformation cog. Due to his pacifism, First Aid attempted to stop him without fighting, but was unsuccessful. Feeling guilty, he resigned from the Autobots and went into seclusion. Meanwhile, the Decepticons used Metroplex's cog to revive Trypticon. To prevent the Decepticons from gaining the advantage, the Autobots managed to steal Trypticon's cog for Metroplex. However, due to the incompatibility of the cogs, both robots began to experience major glitches as they fought. Hot Spot had no choice but to track First Aid down and try to convince him to rejoin the Autobots. Being the only Autobot to understand Metroplex's systems, he agreed and returned to repair Metroplex. This allowed Metroplex to defeat Trypticon yet again, and First Aid rejoined the Autobots with renewed confidence.