The Last life of Prince Alastor

"Three hundred years ago, fate bound Prosper Redding and Prince Alastor of the Third Realm together. Now the human boy and the fiend heir to the demon kingdom must put aside a centuries-old blood feud to save everything they love. Alastor will guide Prosper through the demon realm, under one huge condition: Prosper must enter into a contract with the malefactor residing in him, promising eternal servitude in the afterlife. With Prosper's sister in the clutches of the evil queen Pyra, Prosper has no choice but to agree"--Provided by publisher.