The Grady family, whose name was changed from Garadex, was originally a clan called The MacGrigor living in Celtic Ireland. There was a terrible curse on them, which would turn people into werewolves. Due to this curse, they were thrown out of normal society and lived as outcasts.
The curse on the MacGrigor was due to them breeding with lesser Demons when they first came to the land. They would chain up people who were transformed, instead of killing them as people did sixteen hundred years in the future. They did not know of a cure for the curse, as they had not yet contacted Lord Loss.
A demon named Lord Loss was offered a wager to cure the curse on a member of the Grady family if other family members engaged in a competition. Two people had to fight Lord Loss - one would have to play a five board game of chess against him, while the other fought off two familiars. If either one failed, both challengers and the stricken teenager would be killed. If they won, the person who played chess would go to Lord Loss's universe and fight him there. The chances of winning were slim, but many went through with it and failed or won, but mostly failed.
Although the fight with Lord Loss in his universe would only last a couple of hours, due to time working differently it could be weeks, years, or once, even decades until the fight ended in the human universes time. The person fighting would live in our world as a zombie, while their soul fought Lord Loss. If their soul lost, then the zombie would just die of old age, but if the soul won, then the body would be restored with the soul.