If you are under 18 (or whatever age is appropriate for your location), do not get me in trouble by reading these.
Milurna by Marlene Whitecourt. A brief encounter between D and a female dhampire. WARNING: Explicit sex, blood drinking.A Momentary Lapse by Talia of Eragon. D stays with the Langs to recuperate from his battle with Count Magnus Lee. When weakness of the body leads to weakness of will, D gives in to Doris's wishes. WARNING: Explicit sex, blood drinking.
D is for Dreams by Ruschka. A dreamlike first-person encounter with the hottest D anywhere. WARNING: Explicit sex, blood drinking.
Nature Calls, or The Inevitable Temptation of Vampire Hunter D, by Ruschka. Vampire Hunter D encounters a beautiful blond vampire and his dark-haired friend in this bi-sexual and very erotic crossover. WARNING: male/male and male/female explicit sex, some bondage, blood drinking.
Vampyre Hunter D, by Djake. A hunt in a modern-day setting leads D to a vampire willing to help him overcome a problem. But does D share that willingness? The author's illustrations for "Vampyre Hunter D" are on the first Fan Art page. WARNING: Bondage, sexual content.
Bloodcall by Cody Vampire Hunter D:Bloodlust, D/Meier Link. D has one last encounter with Meier Link, wherein he learns what it is to give in to his vampire nature. WARNING: Explicit male/male sex.
"Bloodcall" is also available at Cody's website, in HTML and text formats.
Red Stakes by
When Meier Link catches Alucard spying on him, he decides
to teach the beautiful young hunter a lesson of pain
"Red Stakes" was inspired by "Blood Bond," a VHD-Castlevania crossover on Mishaela's fanfic page.
Red Stakes 2 by Lady Sharlot. Continued from "Red Stakes." Meier, D, and Alucard make a very hot threesome in bed. Less BDSM than the earlier story. WARNING: Lots of explicit male/male sex, still definitely for the over-18 crowd.
Darkness before the Dawn by Cathy Krusberg. This fanfic page doesn't have a section for fics about sex and violence, but if it did, "Darkness before the Dawn" would go there. A woman at an inn makes a pass at D and gets more than she bargained for. WARNING: This fic contains explicit nonconsensual sex.
Open the Door by Mishaela. D encounters a mutant who loves giving him all that he needs. WARNING: male/male sex, blood drinking.
Mish has written a series that continues "Open the Door." You can read it at Mishaela's fanfic page. More sweet but very hot male-on-male sex. You've been warned! This page also has a Castlevania-VHD yaoi fanfic, "Blood Bond."
Drawing Blood by Cathy Krusberg. What might, just might, have happened after D saved Doris and before he left. WARNING! This story is very sweet and gentle, but it does contain explicit sex.