Many centuries ago, when humanity was on the verge of extinction, the first vampires emerged. These creatures are known as the Moroi - or Purebloods; vampires who had taken over the land as the reigning species. These vampires are essentially revered as royalty, known for their supernaturally ethereal beauty and for their powers; being able to trace their descent directly to the first vampires who had once appeared those many years ago. Nonetheless, there are various Moroi Families, some of whom have more importance than others and make up the Accords - the governing body of vampires who rule over both the vampire and human race.
Below them, are the Blood-Servants. Vampires who, unlike their Pureblood counterparts, were either once human (turned by a Moroi) or are the offspring of two Blood-Servants. Regardless, when a Moroi changes a human into a vampire - a blood servant - the vampire and their future descendants are bound to that Moroi bloodline via a blood-link, and often, continue to serve their respective Moroi households as guardians.
The 'Tainted Ones' are quite literally, beasts in human form, who relentlessly feast upon the blood of both humans and vampires in an endless attempt to satiate their never-ending bloodlust. A Blood-Servant only becomes tainted upon their first transformation; if they do not drink the blood of their Moroi host, their blood becomes tainted and corrupts their mind. Filling them with a bloodlust that never seems to end. Like beasts, these monsters breed very quickly and live in nests; often hunted down by both Blood-Servants and hunters.
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There was nonetheless, a time, before the establishment of the Accords, that the human and vampire races were ruled over by a single Moroi family, known as the Ravnos, who due to their lineage, were much more powerful than any other vampire. The Ravnos Family consisted of two brothers, Mikhail and Set, who were polar opposites of one another. While Mikhail was kind and believed in a pacifist ideology - that humans and vampires could one day co-exist together peacefully - Set preferred to exert his power and fed upon humans indiscriminately, seeing them and the blood-servants as lesser beings. The brothers ultimately came to a clash after both falling in love with the beautiful Moroi, Elena Venturi, who agreed with Mikhail and was loved by all. Her decision to ultimately choose to be with Mikhail did not sit well for the unstable Set, who in a fit of passion one day, attacked and drank the blood of a pregnant Elena, and in turn, caused a miscarriage.
The act itself led to a bitter conflict between the two brothers, the war itself having caused many civilian casualties - most of them human. Mikhail fought on the side of peace, with his fellow Moroi, Blood-Servants and the newly created Brotherhood. A group of human vampire hunters who once drank the blood of the Moroi to enhance their abilities, which helped them hunt Set, his cultist followers and the Tainted vampires who fought alongside him. The war came to an eventual dramatic conclusion, where the two brothers fought one-on-one against each other and thus, led to the defeat of Set, who in his final words, cursed the vampire world, stating that they would never attain peace and one day, he would return to 'finish what he began'. Despite this, the love Mikhail had for his brother proved too strong to let his body crumble away, and so, using their combined blood, Elena and Mikhail sealed away Set's body eternally.
Elena and Mikhail's love, and above all, never-ending loyalty to one another, is a primary example of the love which two vampires can have for one another if they were to solidify their blood-link - another term for soulmates. The reminder of their valiant sacrifice comes in the form of the Eternal Rose; a heartbreakingly beautiful rose which never withers, and contains both Mikhail and Elena's life-force in one - a symbol of their undying and eternal love for one another. It is due to this, that many vampires who marry, must swear upon 'The Rose'.
It was nonetheless after the extinction of the Ravnos Clan that the surviving Moroi created the Accords - deciding that it was better to rule as a Council of Five rather than a single Family ruling over all. The head of the Accords is none other than the Venturi Family, still venerated for their ancestor's honourable sacrifice. The Brotherhood of the Five - the group of warriors - nonetheless became an independent organisation who focused their mission on protecting the human race, who seemed to be constantly victimised by the vampires.