Greg knew that tone - knew Weasley was acting all 'surprised' that Greg wanted to be at chess club. It frustrated Greg that he couldn't think of a good reason why he should be here - it wasn't as if Draco or Pansy would ever come to a club hosted by a blood traitor, nor did Greg think he'd spot anyone else he recognised.
One of Greg's hands curled into a fist as he and Weasley stood staring one another down, neither wanting to be the first to move. His other hovered over the concealed pocket where he stored his wand. It would be so easy to send Ron flying across the room and into his precious chess-pieces. Greg's year of schooling under the Carrows had instilled in him a confidence in his own offensive magic and he had no doubt he could outmatch Weasley, even if he were an auror. Caught between his desire to take action and the nagging feeling that he shouldn't (though why not, Greg couldn't think in that moment) he stood still, scowling, and waited.