The climax of “Steven Universe: The Movie” comes not when the hero battles the vengeful, superpowered alien atop the planet-destroying weapon. It arrives a beat later when the titular Steven and his adversary, Spinel, form a delicate friendship while standing in a smoldering crater of their own making. Steven helps Spinel see that although the trauma she’s suffered can’t be erased, personal growth is good and possible.

Their rapprochement follows a slugfest as action-packed as any you’ll find on Cartoon Network.

And creator Rebecca Sugar had to fight like hell for it.

“I would get these notes that he should obliterate her and rid the universe of her evil,” says Sugar. “That’s really not what our show is about. But it’s what is expected from children’s programming — that if there’s a bad person, you kill them, and then everything will be fine. I just think there should be some alternative.”

It was that kind of alternative thinking by the groundbreaking showrunner that went into creating a boy hero raised by three superpowered, female-coded, nonbinary space aliens — clearing fresh terrain in children’s programming.

Sugar sits in a windowless room inside Burbank’s Cartoon Network Studios, where she is wrapping post-production on the final episodes of “Steven Universe: Future” — the event-series coda to her long-running “Steven Universe.” An animated epic that unspooled over 174 episodes and a movie on Cartoon Network, “Steven Universe” featured a wedding between two female characters before gay marriage was legal throughout the United States. It won an Emmy, a Peabody and a GLAAD Media Award. And it has been hailed for its inclusiveness, its breakdown of gender norms and for the singularity of Steven — a protagonist defined not by his powers (which are awesome) but by his emotional intelligence.

Steven also boasts the goofy sense of humor that appeals to Cartoon Network’s core audience of 6- to 11-year-old boys and engages often in the rough-and-tumble adventuring they crave. Now the “Steven Universe” saga is ending with a four-part finale set for March 27, having managed a magic trick — connecting with its network’s target viewers while also drawing together a devoted, inclusive base of underserved fans who might not otherwise find their way to the network.

“‘Steven Universe’ can truly be watched and enjoyed and loved by a very young audience who’s following a wonderful adventure and a set of funny characters and all the things that make for a great show,” says Rob Sorcher, executive VP and chief content officer of Cartoon Network. “But it also has something for those people who want to dip into it later in life. It is clearly also exploring other themes that are resonating with people.”

Sugar’s relationship with Cartoon Network began in 2010, when she worked on Pendleton Ward’s “Adventure Time.” She created the character of Steven Universe — the child of a human and a powerful alien from a race known as Gems — for an animated shorts program that Sorcher launched in 2009 in part as a talent-development mechanism.

Sorcher had doubts at the time about whether Sugar’s vision could translate into a successful series. “We had always been the boys channel,” he says. Steven, with his three surrogate moms and his defensive superpowers emanating from a large pink jewel on his stomach, was an unconventional protagonist for a boys channel. But Sorcher gave it a series order anyway.

Rebecca Sugar fought to make the “Steven Universe” saga inclusive.

Courtesy of Cartoon Network

“If you just watch the original short, you will see a regular, awkward, hilarious kid, and you see the mastery and the humor of the scenes,” he says. “It’s just a good show. It’s hard to watch even the original short and not be compelled to move ahead with that even if it doesn’t exactly fit with the rest of what has come before and around it.”

Sugar knew she would face barriers. As millennial kids, she and her brother, Steven Sugar (the inspiration for the character and himself an artist who worked for several seasons on “Steven Universe”), grew up devouring entertainment designed for and marketed to boys. They played Nintendo games like “Zelda: Ocarina of Time” and watched shounen anime like “One Piece.”

“I was excited about the context of making something within Cartoon Network, and I was excited about making something that was sort of quote-unquote supposed to be in the boys six to 11 demographic,” Rebecca Sugar says. “When I was young, those were the shows I liked, and I had really no interest in shows that were for girls. I wanted to make the show that I would have liked when I was younger as a nonbinary kid. But I also wanted to make sure that I was making that show without any of the signifiers that I used to understand meant I wasn’t supposed to be watching those shows.”

Sugar identifies as a bisexual nonbinary woman. As a child, she knew that she was bi, though she didn’t come out to her family or her partner — animator Ian Jones-Quartey, who served as co-showrunner on the first three seasons of “Steven Universe” — until five years ago, long after she had embedded in the series a number of queer relationships and characters.

In addition to a bright color palette and silly playfulness, “Steven Universe” boasts a mythological spine that could wow a Tolkienologist. No character better illustrates this than Garnet, one of Steven’s surrogate mothers. A cool, towering warrior voiced by the pop singer Estelle, Garnet is the fusion of two Gems, Ruby and Sapphire, who choose to merge to form one being — though they are able to separate into their individual forms when called for. Sugar based Ruby and Sapphire on herself and Jones-Quartey, and over the course of the series revealed that the relationship between the two characters is a romantic one.

“I really wanted to respect the intelligence and the imagination of our young audience with stories that I personally found interesting.”

Rebecca Sugar

Sugar played the long game with Ruby and Sapphire, not even revealing them or Garnet’s true nature until Episode 52, “Jailbreak.” One hundred episodes later, the two characters enjoyed an on-screen wedding.

“I wanted to give them every kind of romantic cartoon episode,” says Sugar. Over the course of “Steven Universe,” Ruby and Sapphire reunite following a forced separation, argue, even flirt in the middle of a high-stakes baseball game. Their wedding ends with them again forming Garnet, who embraces herself in an emotional dance sequence. “Ultimately I wanted them to have this big, animated wedding. These are all cartoon tropes that I enjoyed when I was younger and wanted for them. And it was extremely difficult.”

Sugar spent a long time pushing for the wedding episode and other instances of queer representation on the show. She was in her late 20s when Cartoon Network gave her the green light — but not before explaining the stakes to her.

“They brought me in for a meeting, and they essentially said, ‘We know that you’re doing this, and we know that if we were to tell you to stop, that would be based in bigotry.’” Sugar was then cautioned that the show could be censored internationally if she continued down the path she was on. “Ultimately they told me in this meeting that it would be my decision if I were going to tell the truth about what I was doing, which in hindsight was a really bold move for Cartoon Network to make, to actually give the decision to speak about this to the queer content creator generating this material.”

“Steven Universe” ended up being pulled in multiple territories, but the show survived. Sorcher credits it with helping evolve Cartoon Network, where 52% of studio production staff is now female. “That’s the wake of ‘Steven Universe,’” says Sorcher, who notes also that the company’s artist population is now far younger than ever.

“It’s created such a wave of inclusive shows and even movies now that are following in that kids and family space,” GLAAD’s Megan Townsend says of the show.

The character Garnet embodied much of the show’s queer representation.

Courtesy of Cartoon Network

Sugar adds that much of what she had seen previously in terms of queer representation in kids programming focused on characters with same-sex parents. “What I really wanted to do was not necessarily that, but make content for queer youth, which when I was trying to do this was met with a lot of opposition because people think that that is not a thing,” Sugar says. “I know for a fact it is a thing, because I was a queer child.”

The same elements that made “Steven Universe,” as Sugar calls it, “a difficult show to program,” in time helped turn it into a phenomenon. Its queer themes resonated with young adults who like Sugar grew up immersed in speculative fiction and genre entertainment but rarely saw themselves reflected therein. And the serialization and complex story world that presented a hurdle for linear viewers when the show premiered in 2013 now invites viewers who will discover it for the first time through streaming apps. As it comes to a close, “Steven Universe” has found an audience as broad as its on-screen cast of characters. But Sugar rejects the idea that because the program is good, it’s not meant for kids.

“I’ve had people tell me, ‘It’s not really a kids cartoon because it’s so much more,’” she says. “I love cartoons, so to me it’s not that it’s more; it is first and foremost a cartoon.” She adds, “From the get-go, I really wanted to respect the intelligence and the imagination of our young audience with stories that I personally found interesting, that I would really want to tell. Anything less I think would be a disservice to them.”

Sugar grins as she avoids talking about her ideas for what could be her next creative endeavor, and insists that she’s focused, once “Steven Universe” is finished, on finally going on a honeymoon with Jones-Quartey. She admits that she has given thought to shifting to adult animation — a field experiencing a boom cycle amid the success of shows like “Bob’s Burgers” and “Bojack Horseman.” But she also indicates that she’s not yet done with kids programming.

“I love making animation for kids,” she says. “I think they’re such a great audience. Their imaginations are so huge. It’s difficult to imagine giving up an audience that’s so open, and so imaginative that you can throw wild concepts in, and wild visuals in, and have your audience be really immersed. I just really love doing this work.”