"Dirty" Dave Duncan is a supporting character in the third story in Four Past Midnight, The Library Policeman.
The Library Policeman
Dave is a recovering alcoholic at the start of The Library Policeman. He collects and recycles newspapers in Junction City, Iowa. Sam Peebles lets him collect newspapers from his house. As events unfold, Dave inadvertently collects and recycles two of the books Sam had checked out from the library. Dave is in an Alcoholics Anonymous support group with, among others, Naomi Higgins (who calls herself Sarah among the group). Dave is an abundantly skilled painter.
Early Life
20-30 years prior to the events in The Library Policeman, Dave is a painter in Junction City when Ardelia Lortz comes to town. She begins to draw in Dave, at first accepting an offer from him to paint her house, then quickly escalating an extremely sexual relationship with him. Dave is troubled by many aspects of Ardelia as he gets to know her better, but she placates him by serving him massive amounts of alcohol, starting his downward slide into alcoholism. As their relationship continues, she allows him to be present while she reads to the children in the library where she first works and then becomes head librarian. She informs Dave (although ambiguously) that she had caused the demise of the previous head librarian after he had forced her to take down a poster that he felt would scare the children. While attending Ardelia's reading sessions with the children, Dave saw the bizarre way she controlled the group, at one time spying on her while she drained "the special tears" from one particular child. Despite his misgivings, Dave remained strongly fixed under Ardelia's spell. As her position grew more tenuous due to a deputy who's daughter attended the reading sessions, Ardelia informed Dave she was going to "rest" soon, and she wanted him to join her. His price for this, she informed him, would be that he would have to kill the deputy's daughter. Dave initially agreed to the price, but began to have second thoughts. He eventually made an anonymous call to the deputy, warning him away from the library. Despite the warning, the deputy presumably pressed Ardelia to the point of beginning her "rest" early, after killing the deputy and two other children.
Some time after his events with Ardelia, Dave became friends with a farmer (and pilot) named Stan Soames. Stan's son, Joey, who was dying of leukemia, was a fan of baseball, cheering for the Kansas City Royals. After Joey was informed that he wouldn't be able to attend any baseball games in person, Dave took it upon himself to paint portraits of every member of the Royals, with each portrait on a baseball with the player's signature. Stan became indebted to Dave for his generosity.