[He's never been the best in social situations, so Arthur is more or less trying to remove himself from this one, or at least make himself as unnoticeable as possible. There's a thick book open on his lap - one he'd been reading for most of the summer - and for the looks of it, he's almost done.

For the moment, he's managing to ignore everyone around him. Having twice as many people as usual in the Slytherin dungeon is making that rather difficult, however]