A show for kids that aired its final season entirely online may not only be the most subversive television event of the year, but it could have the power to change children’s TV forever. Yes, really.

Last night Nickelodeon aired the finale of the animated spin-off series The Legend of Korra, bringing a nine-year journey that started with Avatar: The Last Airbender to a close. But perhaps “aired” is the wrong word. Because, in an unprecedented move, Nickelodeon pulled The Legend of Korra off TV earlier this year and screened almost the entire last two seasons online only. That’s right, something called The Legend of Korra, an adventure show about teenagers with the supernatural ability to manipulate the elements, pushed the envelope so far it got yanked from TV. And last night, during the finale, creators Bryan Konietzko and Michael Dante DiMartino shoved that envelope even further. And they shoved it hard. Kids TV may never be the same again.

Here’s how The Legend of Korra, by breaking racial, sexual, and political ground, became the most badass, subversive show of 2014. (Clearly-marked spoilers for the finale at the bottom of the page.)

The Influence of Avatar: Before they took major risks with their teenage characters on The Legend of Korra, Konietzko and DiMartino created a modern animated classic in Avatar: The Last Airbender. (Not to be confused with the M. Night Shyamalan film The Last Airbender, which, everyone agrees, did a fairly clumsy job of capturing the magic of the original series.) The show, which aired from 2005-2008 on Nickelodeon, was a bona fide hit pulling in huge ratings for the network. The spiritual aspect of the show (mixed in with the adventure of its young characters and borrowing directly from Eastern influences) made it tremendously influential with its young (and old) audience. Not only that, but the success of the first series bought creators Konietzko and DiMartino a lot of leeway when it came to their spin-off, which premiered in 2010. It turns out they would need every ounce of it.

Censorship: It’s always tempting to watch something you’re not supposed to, but this week in particular, with its Sony hacks and cinematic censorship, the notion of watching something forbidden feels like an especially political move. The Legend of Korra was never quite forbidden, never completely canceled, perhaps due to that lingering Avatar goodwill. However, during the show’s first season, it aired in a coveted Saturday-morning slot. After killing off a character on-screen in the Season 1 finale, Korra was considered too risqué and adult for the Saturday-morning crowd and was moved to Friday nights. But Korra continued to air dark material. That, coupled with less-than-stellar ratings, an ill-timed leak of episodes, and any number of mysterious behind-the-scenes factors, resulted in the surprising move to online-only Korra. In its final seasons, Korra became too dangerous, too risky for Nick to air. But that outsider status made it downright irresistible to certain viewers. Especially teens.

Racial Representation: The show doesn’t take place in our world, but, as I mentioned before, it has an undeniable Eastern influence. That’s why the mostly white casting in the Shyamalan movie was so controversial. Listen, whatever Korra is, she’s not lily white. And, despite the fact that children’s television is becoming increasingly diverse, a brave, strong heroine who is not Caucasian is still an important factor.