I made a prediction before that Jeremy would eventually get a mentor of sorts to potentially lead him down a more "gangbanging" lifestyle so I think maybe Billy could be that character.
Personally, aside from the BBC, I don't even think Jeremy is that much of a stereotype, he was a bit of a dork in school and focused on being more of playa after he got to adult life and, while he has found some success, he isn't exactly the hardcore alpha-male harem-owning corrupting god of temptation some people shitpost him as being in this thread. Shit still blows up in his face, women still refuse him, and he is still the butt of the joke with his friends sometimes because he is an actual character.
But of course, in his pursue of wanting to be more of a playa, he could surround himself with some bad company to try and be more of a bad boy, at the expense of potentially becoming even more of a douche to his friends and to women. My original prediction was that he was gonna impress a rapper/gangster type of character during the MMA tournament and be invited to be part of his crew, so if Billy is to be that character we'd probably need a bit of a time-skip during chapter 7.