[The look of oh god why that crosses his face doesn't even come close to Caleb's when someone asks him to lead, but it's still mildly dissatisfied with this turn of events, and he is eager to find someone else he can push responsibility on.]

Ask around. See if anyone's found noticed a shabby wizard skulking around. [He puffs out his cheeks and exhales.] We'll find him. He's clever... He's too clever to go down with the world. He's definitely around somewhere.

[He's mostly reassuring Nott, but he wants to believe it himself. If everyone else is here and not Caleb... Well, that just doesn't seem fair does it? He's no more a shithead than anyone else.]