Slightly startled at the appearance of another person across the table, it took Marcus a moment to change his focus from the game playing over the wireless - more invested than he normally would have been, since it was Oliver's game - to his actual surroundings again. A few years ago, before his time in Azkaban, he never would have been that unaware of his surroundings, but at least it was a sign that he was adjusting to the changes with time, even if he'd rather not have been taken by surprise in the first place.
When he realized who exactly was sitting across from him, Marcus raised one eyebrow as he asked, vaguely sarcastic, "Can I help you, Potter?"