Just some suggestions:
1) There is a fine line between erotica and banal smut that ceases to be erotic. To avoid crossing into smut you should try to limit the amount of extraneous profanity you have in each paragraph. for instance, we know that Stone wants to knock you up and likes to 'breed bitches'. It gets kind of repetitious and needlessly profane the more (and more you repeat it). Also, most people don't enthusiastically repeat ideas like 'I want you to knock me up' without knowing what it means. The readers know what it means, but your character shouldn't and he comes across as dishonest here (which could be good in some stories, but yours is about his supposed innocence pre-Stone).
2) Don't write a character outside your own race. I can tell you are a white dude without seeing a photo. Stone is a totally racist caricature and basing his erotic appeal on that isn't sexy.
3) The conclusion of a piece of erotica often gives the reader at home their money shot by revealing info that makes clear just outside a reasonable doubt that the erotic act/scenario written about (in this case pozzing) happened so the reader can be satisfied the story is near being finished and they can cum. To be successful, no new information should be added at the end, just previously unconfirmed rumors or ideas that gave the protagonist their self-preservationist reasonable doubt. If you want to keep your ending as here, introduce the needles earlier by having them fall out of Stone's pocket (during sex would be great to give your character fear) and have Garret and the protagonist walk by Stone in the park as he's sharing needles with a junkie. If that's when your character realizes his fate, that'd be intense.
You have a good sense of twisted fetish, and I hope you take these as tips from a seasoned/trained writer and not as bitchy criticisms.