Ritual of Shared Blood
When Elan Varlov first became a vampire it was less than a year before he gave the Philosopher's Blood Elixir to those close to him. But before he would share the elixir to any others he wanted to study the abilities and weaknesses of vampires. Unlike most other hungry dead the vampires were closest to living to the point many could not tell the immediate difference between a mortal or a vampire. But with time the experiments turned to vampire blood where they learned of the amazing if addictive properties of the necromaticlly infused vital fluid. Experiments were performed with both living and dead until by accident one of the vampires drew too much from a close friend who had offered their blood. In a panic the vampire fed her own blood to the man who died only to rise as a vampire shortly thereafter. Learning of this method Elan chose only to share the Philosopher's Blood Elixir with those closest to him whom he trusted and instead allowed those already made vampires to expand their number through the sharing of blood.
The vampire will drain all but a small portion of the mortal's blood leaving the mortal close to death before the vampire offers their own blood to the mortal. Upon drinking the vampire's blood the mortal will die as the ingested blood spreads through their mortal body transforming the subject into one of the undead. Depending on the original vampire the newly made vampire will be one to three degrees weaker than the original. Those mortals who have too weak a soul will be reborn as thralls while those who have strong willpower will arise as a lesser vampire.
The Ritual of Shared Blood is performed by a vampire and a mortal they wish to transform into another vampire. The mortal must be from an intelligent species and have blood that runs through their body. A vampire thrall is incapable of performing the ritual even if done by accident the thrall's blood lacks the power and would at best create a zombie.