You can play Blood Knights either solo and switch between both characters to use their individual skills, or invite a friend to join your game and fight alongside them.
Humans have possessed the seal of blood for thousands of years, which has prevented the demons from setting foot on the Earth. It contains the frozen blood of the most powerful, immortal vampire, Kain, and on no account must it fall into the hands of the vampires. After the guardian of the seal dies, the vampires try to acquire the it. They’d better watch out though, because the humans will be deploying their best vampire hunters, like Jeremy, who are determined to stop them.
When the plan seems to fail, Jeremy takes a final, desperate chance and agrees to be placed under a dark spell. Henceforth he is bound to his worst enemy, a vampiress, but this grants him immense strength.
This spell means that the vampiress Alysa must fight with Jeremy against her own race.
Jeremy becomes infected by another vampire during a battle and turns into one of them; he now becomes the target of his former allies while his bond with Alysa remains intact. Together, arch enemies Jeremy and Alysa fight for their existence, and try to regain the seal of blood.