Before Cynder speaks, Asch's gaze is fixated somewhere far to her right. After her voice sounds out he manages to zero in a little better, this time setling his gaze somewhere a little to her left instead. She sounds young, whoever she is, which doesn't do much to reassure him. Anise and Arietta are both young, too, and Asch wouldn't want to take either of them in a fight unexpectedly.

"I could just set the whole forest on fire instead." Which he absolutely will not do; Alexstraza would eat him alive, maybe even literally. The important thing is that he doesn't think Cynder knows that. "Or you could prove that you're not here to try to sneak into the Sanctum." The red flight might be open to visitors from the others, but Asch has no intention of leading someone that might not even be Dragonsworn back to his home.