The slant of her gaze is probably an attempt to be coy, but it suggests even more so that her immortality is held closer to the vest. Not so close she didn't feel comfortable sharing with him, but still.

"He must take trying to kill you as some kind of petty challenge, then. Lucky for him, if he succeeds, he can even gloat at you about it when you come back - I hear death isn't so permanent in this place," Devin remarks idly.