Megatron has just subdued Sentinel Prime and proposed an alliance with Optimus Prime. Optimus is not pleased with the offer.
"Optimus," Megatron said, "are you denying yourself the opportunity to save your home?"
"I'm not the villain, here, Megatron." said Optimus, "I'm not refusing because I do not wish to save Cybertron, I simply do not wish to work with you."
"Why not?"
"Need I remind you of how many of our brethren you have killed in your neverending quest for power? How you cheated your way into getting everything you ever wanted? And now you come to offer assistance to me? Are you sure you think you can get away with everything you've done like that?" Optimus extends his axe. "You're nothing but a traitor, Megatron, and there's nothing worse than a traitor."
"How dare you go making such wild accusations?"
"You literally stabbed me in the back to gain the information in Sam's head. I was dead for days, along with any history we had together. If it wasn't war before then, it was after."
"Optimus, my brother,"
"You do not deserve to call yourself my brother anymore, Megatron."
"But we are, Optimus."
"We were. We had each other for a long time. But that all changed when you betrayed me, your people, your own moral values, for power. You are now my enemy." Optimus buried his axe in Megatron's forehead.
"You've killed your own brother." Megatron said with his dying breath, "Don't you feel the slightest bit of shame?"
"No, Megatron." said Optimus, "I should, but I can't feel sorry for a traitor."