"I admit it is not the cheeriest of topics but ... do you have any books on the nature of the Fade?" It isn't exactly how he'd planned to start, but face to face with Ness, he falters when considering his original, bolder approach. He's almost certainly jumping at shadows, and there's no reason to frighten her if it's only his own melancholy to blame.

(And, of course, there's the years of lyrium use, even if he's stopped. It's never far from his mind, how it might affect him.)