"It hasn't happened to you yet." That's not a good excuse, and voicing it only makes it seem more hollow than it did in his head. After telling him everything he already had, the omission of Overlord is a glaring oversight and one Rodimus knows he can't argue his way out of. Doesn't stop him from trying. "Why should you have to deal with something that hasn't happened?"

Better to keep Drift from knowing the truth. Especially since he was exiled because of a lie that he told, no matter how many time Drift would insist that that was how it was supposed to go. Rodimus refuses to accept that now; not when he has a second chance.

"I don't know. Maybe?" Yes. The answer is yes. "Whatever it was, I didn't want you to do it." Wanting things to be how they were, just for a moment, shouldn't have been too much to ask. "I lost you because of Overlord once, Drift. I couldn't risk it a second time."