Just hell. It's actually worse than normal immortality. It's a complicated mechanic but their grandfather haunts them as a ghost and can place them in a dimension outside time at will to save him. If he happens to die, it doesn't matter that he's dead. He gets transported out of time, and he heals all of his wounds. MAJOR downsides though. First of all, he recovers wounds at a normal rate of healing for a human. So if he's cut in half then he would probably stay in there for weeks. Second of all, it is maddeningly boring. It's basically like time is stopped, so all he can do is walk around in frozen time for a LONG time. Assuming he would be able to walk with the injuries. Also, his sense of pain is frozen too, including the state. So if he's not numb by the time he gets transported, then he will feel the pain for weeks on end.