Massive mega-armies to oppose the heroes. A rich, ever-expanding lore. A warm, delightfully silly sense of humor rooted in character. A forward-thinking approach to inclusion and equality. Meaty, progressive themes. A strong message of love. Avatar: The Last Airbender ran just three seasons from 2005 to 2008 on Nickelodeon, but the DNA of its storytelling and heart effortlessly wove these qualities together to create something that, for the kids and adults alike who absorbed it, became a saga worthy of standing next to Star Wars and Harry Potter.

The 25 Best Adult Cartoon TV Series 26 IMAGES

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Less than two weeks out from the ten-year anniversary of The Last Airbender’s series finale (the epic “Sozin’s Comet” aired July 19, 2008), another animated series that’s just as talented at weaving those qualities together broke boundaries with a collection of episodes that will surely go on to define the series. Not only did last week’s group of Steven Universe episodes change the direction of its epic, sprawling saga, it aired both same-sex proposal and wedding episodes, something unheard of in animated television. Bursting with dynamic action and raw emotion, it’s become clear that Cartoon Network's Steven Universe has filled the space that Avatar: The Last Airbender left vacant a decade ago.Now, before you cry foul, not only am I aware of The Legend of Korra, but recognize that its storytelling scope and themes of progress take that of Airbender a few significant steps farther. But I would also argue that Korra, a far more mature series than its predecessor, was written for the same exact audience that was watching from 2005 to 2008, after they had aged into the more complex issues creators Michael Dante DiMartino and Bryan Konietzko wanted to explore for their second go at that universe.For Steven Universe, meanwhile, creator Rebecca Sugar approached telling her story from the perspective of someone younger to help the show’s weighty themes resonate with audiences of a similar age. On the series, Steven is roughly 13 years old, a year older than Aang and a year younger than Katara.But while both series make their ideas easily accessible, neither talks down to their younger audience, which is likely why adults have responded so fervently to both. In Airbender’s third ever episode, audiences learn that the villainous Fire Nation slaughtered all of Aang’s people while he was hiding in the iceberg, a tragedy that seeds him with an insurmountable guilt that sticks with him for the series’ entire run.Steven, meanwhile, has the expectation to fulfill his mother’s mission heaped on him from the beginning. Like Aang, from a young age Steven is expected to become a savior of sorts. Neither show shies away from the difficult mental state that this responsibility puts both heroes in, whilst slowly maturing them to a place to do something extraordinary when the time comes. Steven Universe is currently at the end of its fifth season, but with the most recent episodes, an endgame for the whole series has been set in motion, one that feels very similar to Zuko joining Team Avatar for the second half of Airbender’s final season.Still, Steven Universe hasn’t lost an ounce of its inherent silliness or warm charm. One of last week’s episodes spends about half its runtime reciting wordplay and puns surrounding the character Bismuth (voiced by Orange is the New Black’s Uzo Aduba). Steven at one point rattles off, “Anyone want to start a small Bismuth?” which is just wonderfully dumb. Airbender had the same affinity for jokes so bad they were good late in its run. Just take “The Ember Island Players,” the penultimate episode of the series that gleefully pokes fun at everything that came before, such as taking notoriously thick-skinned Toph and renaming her on-stage as Tough.But at both series’ hearts is a desire to do some good for their audiences, and maybe the world at large. Airbender is made up entirely of nonwhite characters, since the show takes place in what Nickelodeon described as “a fantastical Asian world,” and its female characters are just as strong, flawed, and fully-realized as their male counterparts. Katara on more than one occasion is told she can’t do something because of her gender, and then proves everyone wrong. Steven Universe, beyond its titular character, boasts a cast of female super aliens, all of whom are queer. There’s also Connie, an Indian-American human on the series who knows her way around a sword. Steven Universe feels like the natural progression of the push for equality, taking up where Airbender and Korra left off.All that boils down to both shows’ larger message of love. At the end of Airbender, Aang doesn’t kill the Fire Lord, he takes away his bending in an act of mercy. Steven similarly solves a major conflict in the show’s most recent episode by simply talking to the Crystal Gems’ enemies. These shows, though hardly afraid to get their hands dirty in some truly arresting action sequences, promote peace.What the heroes have that the villains don’t is the love of their companions. Aang has Katara. Steven has Connie. Sokka has Suki. Sapphire has Ruby. All these characters aren’t just fighting for something, they’re fighting for each others’ right to live—and to find happiness. With so much hate thrown around in the world today, kids need these messages to teach them a more compassionate way. Adult audiences could use the lesson too.

For more on Steven Universe (and the equally beloved Adventure Time), check out everything Cartoon Network has planned for San Diego Comic-Con