Jade-Blooded
The Jade-Blooded are an unpublished additional Vampire Counts Bloodline (type of vampires related by a lineage of being turned leading back to the very first vampires) for Warhammer Fantasy, making them non-canon but still technically part of the IP. It should be noted that they could be considered loosely canon due to certain Black Library mentions, as discussed below.
Created for the Night's Dark Masters supplement for Warhammer Fantasy Roleplay, later released by Steve Darlington (the co-writer with Jody MacGregor) on its own.
History
When Queen Neferata perfected the eternal life experiments of Nagash by inventing Vampirism using her Elixer, she invited her most trusted servants of the court to join her. Harakhte was one of those servants.
While Neferata's cousin Ushoran was her spymaster, being a schmoozer who was popular among the nobility, it was Harakhte who enforced her will on the populace in his duties as Chief Justice and High Executioner. He created the entire justice system of Lahmia consisting of 900 Scriptures which were enforced zealously by the establishment. In extreme age as a human, to the degree that nobody actually knows his true age other than himself, he took a myriad of drugs magical and mundane to survive. This continued as a Vampire, as anything to improve his health was consumed as often as possible.
For unknown reasons before the fall of Lahmia he decided to turn twelve of his most trusted servants into Vampires and head east along the Warhammer Silk Road to Cathay AKA China. Whether this is because he knew of the advancing living Nehekharan army or not is unknown. These servants inherited his frail physical health, and likewise had to rely on constant medical treatments to maintain a semblance of health. Eventually all in the Bloodline wound up with cloudy eyes, translucent skin, and bright green blood which gives the Bloodline its name, as well as using his 900 Scriptures as the tenants of his bloodline.
Once he arrived he established a network of spies in each of the thirteen provinces of the nation, although each one of his servants betrayed him and sought power for their own instead. Harakhte managed to destroy four of the traitors before Cathay was divided into several nations. Some are ruled by his servants directly, some use political puppets, and some are ruled by unknown entities. Each one is in a constant state of scheming and planning that would make Tzeentch require a chart to keep track of, while each pursues the perfection of both traditional ritual and of adherence to the 900 Scriptures.
Canon?
Note that in other continuity, Neferata's Cathayan servant is an emissary from foreign lands named Prince Xian Ha Feng who she sends to Cathay to set up a network of control. Her entire cast of original Vampires other than those from the primary Bloodlines (Ushoran, W'soran, Abhorash, and in later continuity Vashanesh) changes in every description of the origins of the Vampires with some having entirely different names, or are dropped or forgotten in every work. Xian Ha Feng may in fact be considered the canon version of Harakhte and the Jade-Blooded could potentially be canon due to Xian Ha Feng's adventures and influences other than giving Neferata control of the east in the modern day was left undescribed.
Andy Hall (lead writer of Total War: WARHAMMER) has affirmed the that jade blooded vampires exist in cathay in this interview [1].
Relations
Thanks to very little fluff, their political relations are largely unclear.
In some works Chaos is described as having a foothold on the power in Cathay, Tzeentch specifically. Cathay is also described as having a "Dragon Emperor" that has a human form (and may or may not be a dragon that can assume a human form). The Jade-Blooded seem to be a combination of Tzeentch and Nurgle, so their lack of continuity may be from Games Workshop trying to keep the Chaos storyline that they never explored an option, or writers being inspired by the unused Jade-Blooded story. At any rate, the two are not mutually exclusive and are almost certainly enemies since Vampires and Chaos generally do not get along (Heinrich Kemmler excluded).
Since Ogres are a constant threat to Cathay, the Ogres are likely enemies to be exterminated.
Greenskins are also a threat to Cathay, and thus are likely pests.
- Vampire Counts
Although they have little contact with Lahmia, they still maintain loyalty to the tradition of what Lahmia itself once was and since Neferata canonically controls a large chunk of Cathay she is either a rival for power or an ally to some factions; more likely both at once.
Armies
Every Jade-Blooded is revered as a living god by a cult of human followers, while for Undead they prefer Zombies and Wights. Jade-Blooded themselves prefer to avoid combat, transforming into Sneks to escape conflict. Everything involved in the Jade-Blooded is poisonous, from the snakes to their claws, their bite, even the air around them; every contact causes the Wasting Disease from which nobody survives which the cults call a blessing (ensuring that all victims touched by a Jade-Blooded die) and befuddlement as if they smoked some REALLY potent narcotics. Some Jade-Blooded have entirely lost the ability to fight or even kill, becoming like ancient infants that their cultists bring victims to with a pre-slit throat for them to suckle from. Others are more refined, having blood harvested by their cult from offerings which they mix into a hookah to imbibe their smoke.
While technically forbidden from creating new Vampires, it is not a Scripture so the rule gets violated. Backstabbing is as common as Skaven for lower Vampires, keeping the Jade-Blooded the smallest Warhammer Bloodline.
While the physical prowess of the Jade-Blooded is low to non-existent, they gain quite a bit in the trade-off; they can control the minds of thousands of subjects with their voice gestures, far beyond any eye-contact vampire glamour. All Jade-Blooded can hover and fly easily.
Due to never serving Nagash and thus never being cursed for failure, the usual Vampire weaknesses of Sigmar's emblems, flowing water, garlic, and lack of reflection do not affect them. Unfortunately they do suffer from their own unique weaknesses thanks to their original sire's state. These include varying degrees of blindness, weakness to an herbal concoction of sticky rice which diminishes their powers, and a counting compulsion. They also sometimes suffer from allergies to certain metals, Warpstone, tears of mortals, water itself, Warpstone, and still are weak against sunlight. It is unknown if consuming the heart of a Dragon like the Blood Dragons would cure any of these.