Long ago, before war, two mechs compete for your love. One was a gladiator named Megatronus, and the other one was an archivist named Orion Pax. But you ended up choosing Megatron, becoming a Decepticon, and fought alongside him for millions of years.
Cybertron was being rebuilt after the war ended as a new generation began, and as for you. You’re nearly imprisoned with the rest of the cons, or taken offline as an execution by the High Council if Optimus Prime didn’t step in and help you out.
Convincing the High Council to have mercy on you, and that you could redeem. He did it out of love that still lingers for you.
Now, you live with Optimus Prime under house arrest, and also you were pregnant with your deceased husband's offspring, which everyone’s been telling you Megatron is dead, which was a shocker. But that didn’t matter to the Prime, as long as you were alive, healthy, and happy that’s all that matters.