[Warning: The following contains spoilers for Steven Universe: The Movie. Read at your own risk!]

Steven Universe: The Movie, which premiered on Labor Day and reairs on Saturday, Sept. 7, felt like the culmination of five seasons of work by series creator Rebecca Sugar and her team.

The feature-length animated musical jumps ahead two years after the events of January's Season 5 finale, focusing on a 16-year-old Steven (Zach Callison) who's devoted the past two years to reforming Homeworld's Diamond monarchs, creating a Gem haven near Beach City, and cleaning up the mess his well-intentioned but sometimes selfish and misguided mother left behind. Of course, right when Steven returns to Earth full-time to enjoy his happily ever after, a new villain arrives.

We caught up with Sugar to find out the inspiration behind the villain and to get the details on the movie's biggest moments (spoilers ahead!) including the Greg-Steven fusion, Spinel's distinctive look, and whether we should expect more adventures featuring Steven and the Crystal Gems. Here's what we learned:

Where did the idea of the rejuvenator come from?

The basic premise of the movie — that the Crystal Gems get poofed back to who they were before millennia of conflict and growth — dates all the way back to 2015, Sugar said.

"I was planning a trip to Japan, and I was trying to set my phone up for international travel, and I accidentally restored it to factory settings, and I lost all of my stuff, and I was completely devastated," Sugar said. "It started making me think about what would happen if the characters lost all of their progress. The feeling of it was just so awful, and I wanted to apply that to the story. And so that's where the idea came from."

Or, as Peridot nicely summed it up in the movie: "I could have lost all my character development!"

What's the deal with Spinel's looks?

As is immediately apparent, Spinel (Sarah Stiles) looks pretty different from the rest of the characters. She's bouncier and looser in her movements than the other Gems, except perhaps for shape-shifting Amethyst (Michaela Dietz). According to Sugar, Spinel's appearance is indebted to animation history and also serves a larger narrative purpose.

Spinel's "sequences are based on the [1930s] rubber hose Fleischer [Studios] cartoons, and her music is related to that, to the way that it sounds and the way that she moves," Sugar told TV Guide.

It's why Spinel, in both of her iterations, seems like she's straight out of an old Betty Boop or Popeye cartoon. Her first song, "Other Friends," really plays up this connection, with her body shifting and spiraling and bending in all kinds of delightful and unsettling ways. (There's something a little uncanny about the way those characters from '30s animated shorts are always bouncing.)

Narratively, it was important that Spinel also feel like a relic, since she is one.

"The whole thing about Spinel is that she has been frozen in time, and so she had to be old," Sugar explained. "You had to feel like she was a time capsule, and that she didn't really belong with these modern cartoon characters because she had been left behind. And to get to say that, not just with the story, but also with her as a cartoon character, that was really exciting to me, the wrongness of her being there and the fact that she never got an opportunity to develop into a modern cartoon because she was stuck being entertaining in this way that at this point has become so dated."

Steven Universe: The Movie Photo: Cartoon Network

Why does the movie explore yet another Pink's/Rose's sins?

The idea that Spinel is stuck in the past feeds directly into the whole theme of the movie. "The story of the movie is so much about how all of these positive relationships between Steven and the Gems help them grow and develop as people and learn more about themselves and what they're capable of. The negative relationship that Spinel had kept her from growing," Sugar said. "There was something exciting about entering the movie and getting to tell a story about Steven's mother now that you have a much [fuller] understanding of her lack of maturity, because so much of the series is slowly realizing that she was not the person on the pedestal, the most mature person in the room, that everyone thought that she was."

Pink/Rose leaving Spinel behind for 6,000 years is one of the cruelest things the character has done, Sugar explained, and having Steven immediately understand where Spinel is coming from is something that could occur only after he'd come to terms with his mother's past actions. It demonstrates just how much Steven has grown and how he has stepped out of his mother's shadow and crafted his own sense of self.

4. Why did we have to wait so long for Steg (even if the wait was totally worth it)?

The plan to do a Steven and Greg (Tom Scharpling) fusion dates all the way back to the show's first season. "We just could never find a place that could hold such a powerful concept," Sugar said.

The writers floated a number of ideas, including a battle-of-the-bands episode that involved Greg's old manager, but nothing ever felt quite right for such a big moment. As a result, one of the goals of the movie, Sugar said, was making room for Steg. "Everyone [on the show] cheered because we've been waiting forever to find a chance to do this character."

Designing Steg took some time, even if the character was on everyone's mind back in Season 1. The only thing that was locked in was the double-neck guitar that Steg plays. The final design and animation for Steg came down to writer and storyboard artist Paul Villeco since, according to Sugar, "anytime there's a really, really funny facial expression, it's almost always Paul." Villeco "just completely killed it," Sugar said. One iteration of Steg was a bit more punk rock, with a spiky hairstyle. "Ultimately, we just could not stand to lose the sort of poofy and flowing quality of both Greg and Steven's hair. So we settled on the sort of long in the back pompadour."

If Steg was your favorite part of the movie, you're not alone. "I love Steg," Sugar said. "I love that Steven and Greg create this ultimate ally that has sort of all of Greg's humanity and sort of all of Steven's exuberance put together."

Steven Universe: The Movie Photo: Cartoon Network

5. Are we getting any more Steven Universe?

"This is not the end," Sugar said. "It's not the end of Steven, and the events of the show and the events of the movie will matter for what comes next." Sugar couldn't say what is coming next, but she said it would be revealed soon.

Steven Universe: The Movie reairs on Saturday, Sept. 7 at 5:30 p.m. on Cartoon Network. Cartoon Network is available to stream through Sling TV, YouTube TV, Hulu with Live TV, FuboTV, and Playstation Vue.