Regil was once human. He was bitten by a first born vampire and Drake thought he could be the greatest of allies. Drake used werewolve, vampire and his own DNA to keep him alive. It work and Regil became Drake's second in command. Regil off then lead warriors into battle. He also was involed in the coven war. The war that started the feund between the frist born and seccond.
Having Drake's blood in his vains give him all of Drake's powers, except for being able to contol and create both fire and darkness.