Having already reached his own 'oh no' several minutes ago, Megatron has little sympathy for the one Starscream has belatedly arrived at.

"Good. With any luck we ought to be able to work out how to send you back where you came from." He sincerely hopes so, anyway. The last thing he needs is to be saddled with some kind of alternate universe Starscream doppelganger on top of everything else. If he's really lucky, maybe he'll be able to just foist him off on Perceptor and Brainstorm and wash his own hands of the entire thing.

He eyes Starscream critically. "Is there any chance any of your allies will be attempting to follow you here?"