Fulfilling her part of their coital bargain, Allie begins to tell Roland the first (but not last) story-within-a-story that characterizes the entire DT series. When Roland puts a hand on her stomach, Allie "starts violently", obviously jittery about the situation ... but it's clearly not Roland she is afraid of.
The Man in Black entered Tull on a windstorm, shaking the town's residents into silent avoidance. His black robe gave him the aura of a religious man, a notion at odds with the crazy grin he wore.
Allie was the only person who noticed him when he first entered Sheb's, the other inhabitants being caught up with Nort's wake, although their treatment of him before his death was not exactly kind. Even the fact that the man was laid out with a sprig of devil-grass serves as kind of a sick joke. This continued cruelty of a man tortured in life weighs heavily on Allie.
Allie's reaction to the Man in Black emphasizes the parallels between the dark man and Roland. She feels a tremendous sexual yearning, although there is a fear mixed into the carnal jolt that is not present when she lays eyes on the gunslinger. As she pours him the "best" whiskey he requests (without even seriously considering giving him the crap she could), he looks directly in her eyes and the pull between her legs grows to a fever pitch. Allie fears her own sexual urges as they apply to the Man in Black, viewing her feelings as a weakness.
When Allie expresses her frustration with the wake (and the attendants' prior treatment of Nort), the Man in Black observes, "It excites them. He's dead. They're not."
Yes, it's fair to say that the Man in Black traffics with death ... and poor Allie does not know how to deal with her own automatic reactions to the power he has, both over her and in general.