Curiously, it's Percy that looks away first. He can maintain eye contact, but it's not always instinctual to do so. Over a meal, he doesn't need to put on the the proper 'de Rolo of Whitestone' mask and he doesn't know Will well enough to be comfortable with it.

"Percival Fredrickstein von Musel Klossowski de Rolo III, but most people just bother with 'Percy'." Does he need to give out the full name? No, but he started doing it as a way to thumb his nose at danger and the habit has stuck.