Aidan Bok was a Jedi Knight during the final days of the Old Republic and the final days of the Jedi Knights. As a Jedi Knight, Aidan was given the duty of gaurding the ancient Jedi Library on an abandoned space station over the planet of Nespis VIII. When the Jedi Knights were hunted down and murdered by the Emperor and Darth Vader, Bok knew they would be coming for him.
When Bok's time did come, he was unable to defeat the Sith Lord's and their dark power. Seeing this as a failure, and ashamed of his failure, Bok remained on the space station as a disembodied spirit, refusing to become one with the Force. Bok's spirit was mostly concentrated in and around the book, The History of the Jedi Knights.
Years later, a young girl, Tash Arranda, her borther, Zak Arranda, and their uncle, Mammon Hoole, arrived at the space station in search of a project commissioned by Emperor Palpatine, and led by Borborygmus Gog, a Hoole's former colleague. When Tash Arranda opened the book Bok's spirit remained concentrated around, he was set free and helped Tash, her brother and her uncle escape from the space station as well as Gog. Seeing this act as a sort of redemption, Bok finally reconciled with his shame and allowed himself to become one with the Force.