Mersault's ancestors: The alienated characters in Alexanderplatz - Berlin

In the 6th "book" of Alfred Doblin's Alexanderplatz - Berlin, the protagonist and anti-hero, Franz Biberkopf, now unable to partake in petty theft and burglary and unwilling to go back to selling semi-pornographic newspapers, finds another way to make a living as he takes in a teenage runaway whom at first he thinks just needs shelter and affection but soon realizes she needs a roof over her head so she can sell herself out as a prostitute, so he becomes a pimp, her pimp - almost unwittingly (he's very thick). It's not especially clear what role he plays other than living off her wages of sin, so to speak. In fact, one of the puzzling things about this novel is what all these women see in Biberkopf, an ex-con of no particular wit or charm who's barely able to make any sort of living, has no family or friends, and in the 2nd half of the book is severely disabled by loss of his right arm. On that front, one of the more powerful scenes in this section is Biberkopf's tense visit to Reinhold, the guy who got him involved in the botched burglary and actually pushed him out of the getaway car, leaving him in the street to get run over and nearly killed. Reinhold thinks B. is out to kill him, and pulls a gun on B., but B., in his usual passive manner, just wants to talk. R. give him some bizarre fashion advice about pinning his loose right sleeve and encourages him to get a prosthesis. There's a lot of talk about politics as well in this section of he novel, as B. hooks up w/ a guy who brings him to various leftist and communist meetings and rallies, where he taunts the speakers and engages others in debate - claims to hate politics, to be apolitical. We can certainly see in the discontented, alienated outsiders, Biberkopf and others, the ancestors of the post-war existential heroes (e.g., Mersault) and the beginnings of the right-wing, fascist movements soon to sweep through Germany, Italy, and elsewhere. Not sure where any of this is heading, but nowhere good, obviously.