"I will never ask you for anything except to dream sweet of me"

BJ (before Jupiter)

In the beginning, Sothis, believed to be a Goddess, descended upon Fódlan, taking a human form to live among those already living there. Therefore, it wasn't actually the very beginning, but it is the beginning of our story. In reality Sothis was not really a Goddess, rather an alien from a faraway place. She had opened a rift in spacetime to get to Fódlan. Therefore, those born of her blood were also inhuman. Not truly aliens, as they were created on Earth, but outsiders nontheless. Sothis, in her eternal generosity, had also brought magic to Fódlan. Not real magic, it was a combination of alien technology and energy from the rift, but to those in Fódlan it was magic. Fódlan, rarely visited by foreigners, remained mysterious to most of the world, their alien residents unknown. In the future, people will talk about it as though it was a myth, most unknown and wholly unreal.

Origins

Jupiter, originally Javic, was born shortly before Nemesis massacred the Nabateans. Cichol, focused on protecting Cethleann, left him in the care of a family in what would later become the Holy Kingdom of Faerghus. Seperated from his father and his culture left him to grow up feeling isolated from those around him. He grew very lonely, living life as a mercenary for a long time, doing his best to keep to himself so no one noticed he didn't really age. There came a time, in a thousand years, where his father came back for him. Now wearing a new name, Seteth, he asks for Javic's aid. Like any man desperate for his fathers approval Javic agrees, joining the Church and masquerading as Seteth's younger brother. The resent he has for Seteth and the Church he represents grows over time, leading to him standing by Edelgards side during the war. In the end, he, a child of the Goddess the same a Seiros was, is the one who kills her. He takes her title of Saint after he takes her life. After this he finds a way to close the rift, and with this his job is done and he bows out of Fódlan gracefully.

AF (After Fódlan)

He travels the world for a time. In the end he finds a home in the UK, despite the fact that he doesn't have a real home, does he? He doesn't stay there exclusively, he travels around, he learns, he makes friends just to lose them, he lives. He runs into a certain man a lot, a Captain Jack Harkness. Maybe, if he knew Jack better, he'd learn that they have the same birthname, but that's not important to their stories. They are simply two immortals who run into each other often, they share stories, drinks, and company then part never knowing if they will see the other again, though they both secretly hope.

Torchwood Time

Jupiter has always been vaguely known to Torchwood, never enough of a threat to target, but definetely enough of a bother to shoo away. He's always been fond of Torchwood Three, maybe the rift in Cardiff reminds him of home. He's also always been fond of bothering Jack, they're alike in a few ways, and they find each other entertaining. So when Jack takes controll of Torchwood Three in 2000 it's a match made in Heaven. Kind of. Jupiter is flightly and skittish, so sure, he helps Jack sometimes but he holds tight to his mercenary roots. Shit happens, he changes, he works for Torchwood full time eventually, needing the stability.