Ah yes. Human familial relations. Megatron hasn't really bothered remembering more than he has to about humans, and he also doesn't really care. However... he's going to be stuck with this one for a while, and he can't dismiss the possibility that they might at some point be joined by the friends she mentioned... in which eventuality he'd prefer not to be immediately clapped in irons by alternate reality Autobots even less willing to buy the idea of his defection than this human is. He might as well make a vaguely positive impression – or at least avoid making her any more actively upset than necessary.

"... My grasp of the precise implications of 'son' is a little loose, I'm afraid," he says, glancing down the long street they've stopped in the middle of. "But if you're going to explain I suggest you do so while we walk; clearly we cannot afford to stand around."

That glance becomes a longer look, and a look of faint suspicion crosses his face. Something about that direction in particular seems to draw him to it, for no reason he can account for. He doesn't like it. But something has to be exerting that effect, and while he's disinclined to blindly obey this foreign impulse, it bears investigating... especially when right now it's the only lead he has to pursue.