Maybe it's the tavern surroundings, reminiscent of a bar where he lived once; maybe he'd have found the man vaguely familiar-looking anyway, but seeing him seated at the wooden table with a drink in his hand, Edgar is sure he's seen him before. The half-missing leg is another jolt of familiarity, when he sees it.
He isn't staring exactly, but Gaeta may notice that he's glancing over repeatedly.
Oak & Iron
He isn't staring exactly, but Gaeta may notice that he's glancing over repeatedly.