Fate/UnAble

There is a certain story in the most famous book in history. The First Murder, committed by a jealous brother, who was then subsequently punished for his crimes with an eternal life of suffering. But this is not the story of that brother, no, it is of the other brother. The one who died, Abel bin Adam. After his death, the constant cycle of murder and vengeance had started. Cain was banished by his own father, but what that murderer had done couldn't be reversed. Yet the one to commit the next murder was not Cain, nay, it was Abel himself. Arisen, back from the dead, back for blood. Abel wanted vengence, and he'll have it no matter the cost, even if it meant making a deal with the very devil who had orchestrated everything behind the scenes. But a deal should be an equal exhange, so what did he lost? What did Abel sacrifice for that opportunity to kill his brother? Everything, yet nothing at the same time. For he had just become like his brother, immortal, but unable to live.