In the noir fic they're not already together, see... Jeb is the "detective" role, and Roland the "random hot chick" role. Which gives them a license to flirt back and forth outrageously.
Have you read up to chapter 3? I'm working on 4 right now, and in this one they get some flirting action on. Before that the most that really happens is that Roland rather insistently picks up the tab for their lunch date.