Vassalord

A Shoujo Manga by Nanae Chrono about a cyborg vampire named Charley who happens to be a vampire hunter for the Vatican. No, really. Since it's a sin to ingest the blood of a human, Charley lives off his master, playboy Johnny Rayflo, also a vampire. Cue Unresolved Sexual Tension and buckets of Ho Yay. The first four volumes are available in English from the now-closed Tokyo Pop.

Tropes:

 * Anime Catholicism
 * Anguished Declaration of Love: Sort of. Charley uses the lines of the Phantom Of The Opera - because it's, well, appropriate - to finally yell at Rayflo how much he loves him and can't stand him being with Barry (allegorically). Rayflo tries to brush it off but for once Charley is pretty damn persistent.
 * Anywhere but Their Lips: Of all the places Charley kisses (and bites) Rayflo, none are on the lips. All the better to heighten the Ho Yay!
 * Author Appeal: See picture.
 * The author's surprised it worked.
 * And we love her for it.
 * At the Opera Tonight: Charley is invited to one in Chapter 16. He and Rayflo even directly quote a few lines the Phantom of the Opera.
 * Attractive Bent Gender: Rayflo in chapter 2. And boy, does he get a lot of stares.
 * Battle Butler: Rayflo's cat.
 * Can't Live Without You
 * Cannot Spit It Out
 * Cheshire Cat Grin: 86
 * Cloudcuckoolander: 86, who spends most of his days high as balls and is convinced angels are talking to him. Rayflo also has his moments.
 * The Cuckoolander Was Right: The angels helped him track down Charley and Craig apparently.
 * Cold-Blooded Torture: Barry has an unfortunate fetish:
 * Cowboy Cop: Craig.
 * Deadpan Snarker: Craig.
 * Deal With the Devil: see the above Complete Monster entry.
 * Destructo-Nookie: Charley seems to think attacking Rayflo with assorted heavy weaponry counts as foreplay. Rayflo seems to agree.
 * Double Entendre: Rayflo's nickname for Charley, "Cherry," is a reference to him being a virgin.
 * Raylfo's countless "suck me"-type comments. Amusingly appropriate considering they're vampires.
 * Elegant Gothic Lolita: Princess Marie.
 * Even the Guys Want Him: Rayflo.
 * Fan Service: Boatloads of it. Though it turns to Fan Disservice whenever Barry shows up.
 * Femme Fatale: Rayfell. Yeah.
 * Flash Back: Most of the background is explained entirely through assorted flashbacks.
 * Foot Focus: At least, toyed with the first time we see Charley feed on Rayflo.
 * French Maid: Rayflo and Charley's maid, who is also their cat.
 * Getting Crap Past the Radar: One wonders how much radar there even is for this series, given how it keeps dancing along the line between heavy Ho Yay and plain old Boys Love. However, the scene that really sticks out is the one where Rayfell is seducing Charley, and she stuffs her hand down his pants and starts giving him a handjob, and if you squint, you can see the outline of Charley's, er, area.
 * Girlish Pigtails: Cheryl.
 * Gorn: The in Volume 3. Also see under Squick.
 * Green-Eyed Epiphany: although Charley doesn't want to admit it (and is STILL in a fair amount of denial about it), everytime Rayflo pays significant attention towards someone else or lets them feed on him, he tends to get very jealous. However, this is taken to a whole new level when Barry comes into the situation and he pretty much loses it at the thought of them together, despite the fact that he knows that Rayflo hates it.
 * Half Identical Twin: Rayflo and Rayfell.
 * Cheryl is basically a loli version of Charley, at least in appearance.
 * Hemo-Erotic
 * Heroic Dog: Also a cyborg.
 * Horny Devils: Barry.
 * Humanity Ensues: Rayflo's cat.
 * I Know Your True Name: Figuring out, is what gives Cherry the power to defeat him. In order to do it, however, Rayflo has to
 * Intimate Healing: Vampiric Intimate Healing!
 * I Want My Beloved to Be Happy: The original reason why Rayflo gave up Charley to the church when he was a child.
 * Keet/Psychopathic Manchild: 86, type B. He even gets blush stickers.
 * Kiss of the Vampire: Sort of. Plus it's a vampire-on-vampire example.
 * Little Miss Badass: Cheryl.
 * Lolicon: Rayfell and Cheryl's relationship has... shades of this.
 * Mad Eye: This is 86's default expression. And when 86 gets serious, somehow his eyes get even more crazy looking!
 * Making Love in All The Wrong Places: In the back room of a church, in an airplane bathroom, in a prison-cell, in an opera house...
 * Meganekko: Charley and Cheryl,.
 * Mile-High Club: Charley and Rayflo. Almost.
 * Mr. Fanservice: Rayflo.
 * Ninja Pirate Zombie Robot: Charley's a cyborg vampire who works for the Vatican.
 * Justified in Volume 5.
 * Charley also has a robotic rottweiler. He helps him fight crime.
 * Older Than They Look: Charley is 145, Rayflo's hundreds of years older. Likely applies to almost all the vampires that appear.
 * One-Man Army: 86.
 * Opposite Sex Clone:
 * Our Vampires Are Different: The first volume is peppered with references to Eastern European folklore, like the case of Arnold Paole, boneless vampires, krsniks and dhampirs. (Which was fortunately mostly explained, either in-manga or in the footnote page.) Rayflo has demonstrated the ability to walk around in sunlight and transform into a flock of bats, and sleeps in a coffin filled with dirt.
 * Panty Shot: Rayfell. They were lacy.
 * Power Perversion Potential: Rayflo's regeneration powers have proven... useful.
 * Rape As Drama:
 * Moresoever, there is heavy implication that for hundreds of years before hand, their relationship consisted of  chasing after   and repeatedly   him when he caught him. It runs very close to And I Must Scream territory.
 * Robot Maid: Rayflo's maids, sort of.
 * Rayfell's too?
 * Sacred First Kiss: Rayfell took Charley's, much to Rayflo's annoyance.
 * Scarily Competent Tracker: Barry, when you think about it. Also, 86.
 * Sexy Priest: Charley, although he's not technically a priest. He'd really like to be one, though-- At least he's pretty holy. (All things considered.)
 * Shotacon: Despite their current relationship, this trope is averted with, and referenced when Johnny's getting jealous of Charley paying Harold attention.
 * Rayfell and Cheryl are, again, a Lolicon version, except they seem to be waiting until Cheryl's a vampire (or at least legal)... Probably.
 * Shower Scene: Right there in Chapter One.
 * Sinister Scythe: Cheryl uses one.
 * Smoking Hot Sex: Rayflo has a habit of doing this. Of course, he seems to chainsmoke.
 * Smoking Is Cool: Rayflo and Craig.
 * Spotting the Thread: When Rayfell is pretending to be a genderflipped Rayflo, Charley finally figures out the ruse when she kisses him and he notices that she doesn't have Rayflo's forked tongue.
 * Stalker With a Crush: Barry.
 * Tall, Dark and Snarky: Rayflo and Craig. Rayfell too, despite being female.
 * Technical Virgin: Charley.
 * Undying Loyalty: There is quite a lot of this running around. Including the pets/combat partners/servants.
 * Vampires Are Sex Gods
 * Visual Innuendo: Charley impaling Rayflo's torso with a huge phallic spiked rod, among many, many others.
 * Voluntary Shapeshifting: Barry. We get to see him do it twice in Chapter 8. From male, to child, to female.
 * Walking Shirtless Scene: Rayflo always seems to have his shirt unbuttoned, if not completely off.
 * White-Haired Pretty Boy: Barry. Charley too, though he doesn't fit the usual characterization.
 * Wife Husbandry: Apparently Rayfell's plans for Cheryl, who seems to be quite happy with it as well.
 * Words Can Break My Bones: Reading the Bible has this effect on vampires.
 * Yandere: Dear god, Barry. With a liberal helping of Squick.
 * Yaoi Guys: Charley and Rayflo, duh.
 * Yandere: Dear god, Barry. With a liberal helping of Squick.
 * Yaoi Guys: Charley and Rayflo, duh.