Aha, got him dead to rights! Phrasing. This version of Avan is very much alive and very capable of hearing everything that Popp has to say. He stops messing around with the bandages so he can make direct eye contact without turning himself into a mummy.

"Heheheh. Whaaat, knowing more about you just means I can be a better friend, right?"

He's not sure if Avan's other, older friends know?? Matoriv never said anything, but maybe he just respects Avan's privacy?? Sure, he certainly does not respect Popp's, but it is a different dynamic. He does not know about Roka and cannot ask about Roka, especially now that there is a chance that Avan could have been in love with him?! Sometimes you travel with a group of people and a love triangle breaks out and someone has to either nobly step out of the way or get rejected at some point! One of Popp's deepest fears is being the guy who gets rejected.

"And I really do think of you as a friend, Avan. Master Avan is Master Avan, but we're on more equal footing, you know?"

Sure, they've never fought a dark general together or anything, but that's not actually a prerequisite for being friends, it is just something that keeps god damn happening.