The way that Edward goes unnaturally quiet at that is an alarm bell, and the final straw of suspicion that Pride needs. He lifts a hand to wind around her wrist, holding it there, not painfully, but not exactly gently, either.

"...Not doing what?" he responds quietly, tilting his head slightly. It would look almost curious if not for the way he's looking at her- there's a darkness in his eyes that is decidedly unlike Edward Elric's usual expression, at least when it comes to Winry. "You're not making any sense."