During production of the film
Serenity, Book's first name was Meria, and it appears as such in the documentary "Re-Lighting the Firefly". However, by the time the film was completed, Joss Whedon changed his first name to Derrial, which is the way it appears in all printed official works based on
Firefly. Casting Glass, a veteran actor well known for his role as Detective Ron Harris in the television
sitcom Barney Miller, had rarely tackled the science-fiction genre and was hesitant about this role when his agent approached him. However, once he read the script he "...fell in love with it". One of the underlying aspects of the show is Shepherd Book's secret past. He holds some sort of high priority status within the
Alliance, and on numerous occasions has demonstrated a depth of knowledge in a number of fields one would not expect a clergyman to be familiar with, including space travel, firearms, hand-to-hand combat, and criminal activity. Glass enjoyed this aspect of the role as well: "Though rather mysterious, it was absolutely clear that he had had a very full life before he went off to the monastery and took on that responsibility. I loved the fact that he could save your soul but he could also kick your ass. That's a really great combination to play." In the DVD commentary
Firefly, Whedon states this is due to Early's intuition and ability to quickly size people up. He also comments that Early's methods for dealing with each crew member are custom-tailored to their personalities. Early disposes of Mal in a straightforward manner; Whedon then notes that Early's method for taking out Book is equally straightforward, alluding to a similarity between the two otherwise different characters. Another hint to Book's mysterious past is shown in the episode "
Safe". When Book is accidentally wounded, Mal is forced to seek medical help from an Alliance cruiser. The commanding officer, after tersely dismissing Mal, changes his attitude once one of his officers shows him Book's identification. Though the exact information on the card is never shown, the crew does note that it affords Book urgent and immediate access to the medical facilities on board, as well as free passage for
Serenity without the expected inspection. Several other episodes contain allusions to Book's past; in "
The Train Job", he is aware of the identity of crime lord
Adelei Niska, while in "
War Stories", he displays a working knowledge of high-powered weaponry, first to identify sharp-shooters and later to take part in a coordinated assault against Adelei Niska's space station. On the 2007 Browncoat Cruise, Ron Glass revealed with Whedon's permission several facts about Book, including that Derrial was not the shepherd's real name, but the name of a man he had killed. Also, a "part of [him] is artificial, he found God in a bowl of soup, and [he] is best known for his greatest failure". This was part of an announcement for a comic book series based on Book's past, titled ''The Shepherd's Tale''. It was later announced that this would be seeing print in November 2010, and was subsequently released November 3, 2010. During the Dallas Sci Fi Expo 2012 Ron Glass said he did not like the fact that Book had never been married, and would like to have married at some point in the show. ==Character biography==