Warning: spoilers for the movie ahead.
"Star Wars: The Force Awakens" brought original characters from the "Star Wars" franchise back to the screen, but when R2-D2 finally popped up, the beloved droid was in "low-power mode."
The old droid had apparently been in that state since Luke Skywalker disappeared following Kylo Ren's transition from his old self Ben Solo, a Jedi trainee, to the Dark Side.
After some earlier attempts by BB-8 to wake him up, R2 finally becomes responsive after Rey, Poe Dameron, Chewbacca, and the rest of the Resistance members return from their mission to destroy Starkiller Base.
But in the film, there isn't much explanation as to why that is the moment he would leave his self-induced slumber. Once awake, he's able to complete the map to the missing Skywalker, making the barely there droid a crucial plot point.
In the official novelization for "The Force Awakens," author Alan Dean Foster dives further into what exactly stirs R2 from his low-power mode.
As members of the Resistance are gathered to discuss the location of the missing map piece, Rey says that the First Order has the part they need because "they extracted it from the Imperial archives."
Admiral Statura (portrayed by Ken Leung) explains why that makes sense: "The Empire would have been looking for the first Jedi temples," he says. "In destroying all the Jedi sanctuaries they would have acquired a great deal of peripheral information.”
Just like in the film, as a discussion about the missing part of the map occurs, R2 overhears and awakens, and he comes beeping into the room.
C-3PO has the ability to translate R2's beeps and tells the group that R2 might have the same map, having tapped into the data before.
“If the information you are seeking was in the Imperial archives, he believes he may have catalogued that data," C-3PO says. "He’s scanning through it now.”
R2 finds the rest of the map and projects it, allowing BB-8 to project his piece and complete the map.
Director J.J. Abrams and cowriters Lawrence Kasdan and Michael Arndt backed up this reasoning in a Q&A following the film's premiere, according to Entertainment Weekly.
The group thought back to the original film, 1977's "A New Hope," when R2 tapped into the Empire’s mainframe while searching for Princess Leia.
“We had the idea about R2 plugging into the information base of the Death Star, and that’s how he was able to get the full map and find where the Jedi temples are,” Arndt said.
Abrams followed up that it wasn't explicitly detailed in the film to avoid focusing on past events.
“But the idea was that in that scene where R2 plugged in, he downloaded the archives of the Empire, which was referenced by Kylo Ren,” Abrams said.
Later, BB-8 says something to R2 that starts to stir him awake.
“BB-8 comes up and says something to him, which is basically, ‘I’ve got this piece of a map, do you happen to have the rest?’” Abrams said. “The idea was, R2 who has been all over the galaxy, is still in his coma, but he hears this. And it triggers something that would ultimately wake him up.”
The director also said that waiting to bring R2 back until after Han Solo's death was purposeful: “While it may seem, you know, completely lucky and an easy way out, at that point in the movie, when you’ve lost a person, desperately, and somebody you hopefully care about is unconscious, you want someone to return.”
More From Business Insider