Main article: Arcee (G1)/2005 IDW continuity

Sibling of Galvatron, Arcee of the Darklands was an ancient warrior, hailing from the prehistoric era that predated modern Transformer civilization, serving under the fearsome tyrant Megatronus during the wars that led to the unification of Cybertron under the Thirteen. Origin Myths "Forged male," Arcee would eventually seek out the assistance of the amoral scientist Jhiaxus for assistance, after the First Cybertronian Civil War. Seeking to reintroduce the concept of "gender" to the species after its mysterious elimination, Arcee would be altered at the genetic level—but Jhiaxus's callous treatment of his patient would change Arcee into a raging berserker. She could only focus on exacting bloody revenge against him and all that he had created, Spotlight: Arcee Post finally getting even with her tormentor after the thwarting of Nova Prime's Expansion. Spotlight: Sideswipe

It would not be until after the end of the Great War that Arcee would truly embark on the long road to recovery; first falling in with the amoral Prowl as a private enforcer, A Better Tomorrow and later with Optimus Prime, The Mind Bomb Arcee was able to slowly work past her many demons, finding companionship, camaraderie, and even love in her new role as Optimus Prime's advisor—having lived through the era of the Thirteen and experienced their many atrocities firsthand, Arcee remained unafraid to call out her new leader as he verged closer and closer to repeating their mistakes. But when those mistakes came home to roost in the form of Unicron, Unstopped and Unstoppable Arcee played an instrumental role in the battle against the planet-eater before settling into a new life on Earth with Aileron.

https://tfwiki.net/wiki/Arcee_(G1)