While writer/director Rian Johnson is the shepherd of the second film in the new Star Wars trilogy, Star Wars: The Last Jedi, it turns out he also had a significant impact on the film that precedes it, Star Wars: The Force Awakens. Lucasfilm has been on a pretty quick track with these new Star Wars films, which was somewhat hindered by script delays on The Force Awakens that saw that movie push its release date from May 2015 to December. That shift meant that while J.J. Abrams was still making The Force Awakens, Johnson had to be fine-tuning his script for The Last Jedi so production on that movie could begin in early 2016 with pre-shoots taking place as early as Fall 2015. But as Johnson dug into his story, he discovered one aspect of The Force Awakens that may become a hindrance—so he asked Abrams to change it.

Indeed, in speaking with EW, Johnson revealed that he asked Abrams for a big favor: change the ending of The Force Awakens. That film famously concludes with Rey (Daisy Ridley) approaching Luke (Mark Hamill) atop a deserted island and handing him a lightsaber. But she didn’t make the trek alone—she was accompanied by R2-D2, an old pal of Luke’s. Originally, however, a different droid was with Rey:

“Yes … The big [favor] was, I asked if R2 could come with Rey, and if BB-8 could stay behind with the Resistance,” Johnson says. “Originally it was BB-8 who went with Rey, which makes sense for the story in a way. But I asked, ‘Can you do me this solid and switch the droids?’”

Obviously Abrams acquiesced, and it’s R2 we see with Rey instead of BB-8, who stays behind with a comatose Finn and the rest of the Resistance. As we’ve seen in the Last Jedi trailer, BB-8 is embroiled in shenanigans with his old buddy Poe Dameron (Oscar Isaac) and Finn, but if he was with Rey and Luke, it’d be tough to get him back into that mix.

As with The Empire Strikes Back, it very much appears as though the characters of this new Star Wars trilogy will be somewhat scattered in The Last Jedi. And as Johnson was crafting the story, he obviously decided it may be better for BB-8 to be hanging with Poe and Finn and have R2-D2 reunited with Luke and tagging along with Rey. This offers a new dynamic, as we already saw Rey and BB-8 bonding all throughout The Force Awakens, only to briefly be reunited with Poe at the end of the film.

But when Johnson first sat down to write The Last Jedi, he tells EW that Luke was his primary concern:

“Figuring out where his head was at was the very first thing I had to do when writing the movie. I had to crack this. And it had to be something for me that first and foremost made sense. Why did Luke Skywalker go off to this island?” Johnson says. “That was the starting point, and that’s what the entire movie explores… There has to be a good reason that makes sense to him [to run away] — and to some degree makes sense to us.”

So just as Han Solo was a central figure in The Force Awakens, it very much sounds like Luke is the focus of this follow-up. We’ll find out all about it when Star Wars: The Last Jedi hits theaters on December 15th.

For more on The Last Jedi, peruse the recent links below:

• Here's All of Collider's Star Wars Celebration Coverage
• 'Star Wars: The Last Jedi': Go Behind the Scenes with Rian Johnson's Candid Photos
• 'Star Wars: The Last Jedi' Trailer Breakdown