Drift, I think you needn't worry so much about if you have done enough. You've built yourself a reputation amongst the Autobots - Prime himself selected you to go with him to Vector Sigma. There are very few that would associate your name with the acts that Deadlock committed. In that regard, you've redefined yourself and have earned your atonement that you've so desperately fought for.

[ that's answering the 'how do you know' question. to Megatron, it doesn't seem that Drift has really looked back at all - only his insecurities are holding him back. things that are, really, already washed clean.

Megatron settles a hand on Drift's shoulder. looks like some encouragement is needed here. ]

Do you really think, now that the air has been cleared, that you wouldn't be welcome back on the ship? It's time for you to decide what path to follow - be it with a faction or otherwise - without lingering guilt and the desire for atonement or trying to appease your peers. Decide what you want instead of settling and giving up.

[ then he pulls said hand back and settles once more into his position. ]

I do understand, to a degree. When I went ahead and officially disassembled the Decepticons, I broke all contact. Thus I find myself on a ship with a chance of being attacked at any given moment. Not that I would blame anyone for it at any rate.