He was originally an agent in the 24th century, but during a mission, he accidentally came to a space station in another time and space, and he could not return to Earth.
Assassination, killing, hiding, changing identities, the self that has been hiding in the dark can actually be erased from the past and live with a new identity.
She always thought that it was her choice that made her previous life dark. In fact, the darkness was always around her, and she had to fight bravely!