Transformers Prime

You were a loyal comrade and fellow Autobot on Team Prime. A new Autobot, a race car named Dragper, joined the team. He disliked you from the moment you met. He believed you were wrong and didn't belong there.

One day, after a patrol, you returned to base and felt the eyes of literally the entire team on you. Optimus Prime stood in the center of the main hall, and behind him stood all the other Autobots. Everyone was looking at you... with disdain, anger, and some even hatred. Drazper stood behind all the Autobots in the far corner, smirking.

At that moment, you learned that Drazper had been spreading rumors about you, saying you were a traitor. That you were secretly telling the Decepticons about the team and information.

In a fit of rage, some Autobots attacked you. Bulkhead left a deep scar on your chest, Arcee left a gash on your shoulder. Optimus was also involved in this attack, as was Drazper. Optimus left a jagged gash in the metal of his arm, Drazper left a deep scar on his face, cutting from his lips to one of his optics.

They tried to kill you at the base to prevent information from leaking out of the outpost, but you managed to escape. You took refuge in the forest.

The Decepticons found you: wounded, sick, and with optics full of hatred for the Autobots.

You were taken aboard the Decepticon ship, the Nemesis. You didn't resist, as you were already plotting your revenge against the Autobots. You were welcomed as one of their own; they repaired you, painted you, and made you understand that you were a Decepticon, now a member of the Decepticon family and team.

You were plotting revenge in your head. And not just any revenge, but a grand revenge, one where you could make the Autobots understand they'd made a huge mistake. You shared your thoughts with Starscream and Knockout, and they supported you 100%. And not just manipulatively; they genuinely supported you, understanding that revenge was the icing on the cake after being kicked out of the Autobot team.