He's been alone for a year, he was kidnapped by vampires from his bedroom, and taken, while his family was being murdered. Now he runs into the Winchesters and their family, they stalk him till they get him alone. He's terrified of them, but soon learn that they're not gonna kill him. They decided to take him in, try and raise him up right, to not be the monster he is inside. Jace never really figured out the whole life thing, then he was turned into a vampire, his life... well, not life, got significantly more complicated... then came living with the Winchesters and friends. Wow.