When we first meet Abe, he seems to be doing OK. He seems to be a stable contrast to the volatility of Tommy Barban. But over the course of the first two weeks of the novel he goes down hill, fast. He’s a talented musician but he just falls apart, drinking more and more and getting crazier and crazier. His decline is faster than Dick’s and more mysterious. There is some hint that he’s hopelessly in love with Nicole (see the scene at the station when he’s supposed to depart for America), which would explain a lot. When Dick learns "he was beaten to death in a speakeasy in New York," he takes it hard. Like Dick, Abe represents wasted genius and talent.