Cartoon Network's animated titan Adventure Time is a huge hit for the network, but still primarily seen as a cult show, especially for its (sizable) adult audience—only nerds and stoners watch cartoons about kids fighting monsters, right? That reputation isn't helped by the fact that the first season of the show, the only one streaming on Netflix, is more directly aimed at youngsters, with less emphasis on larger story arcs and a narrower focus on the two heroes, Finn and his magical dog Jake.

But if you press on through Adventure Time's later seasons, it becomes pretty quickly apparent what a formally adventurous show this is. It's become appointment television in its fifth season, which began way back in November 2012 and ended last night after 52 episodes (the show has aired 156 11-minute episodes in total since beginning in April 2010).

For those that don't know, Adventure Time is set in the Land of Ooo, a magical world strewn with candy, magic, and monsters that, the viewer eventually pieces together, is what emerged on Earth after some sort of nuclear war cataclysm. Finn is the only human around, and he has an adventurous soul, running around completing quests and fighting monsters. But he's also aging (he was 11 years old when the show began, and he's about 15 now) and that comes with a developing interest in girls and growing, gnawing existential thoughts about his place in this strange world.

But Finn isn't only what's important about Adventure Time anymore, and the show's format has gotten more and more transmutable (Finn and Jake will not even appear some weeks). Adventure Time has some of the best-written female characters on television, too, all of whom function as far more than romantic foils/objects of affection for Finn. Princess Bubblegum is a deeper and more thoughtful portrait of a well-meaning Type-A personality than most primetime shows would allow. The Flame Princess, who embarked on an abortive relationship with Finn this season, is a teenager whose raging emotions/hormones leave her scorching hot to the touch and thus difficult to break through with.

Marceline the Vampire Queen, introduced as Bubblegum's polar opposite, is a raging id of an immortal girl who does whatever she wants, sparking both jealousy and irritation in her buttoned-down counterpart. But she was the focal point of some of this season's most powerful episodes, which flashed back to her life before the apocalypse that transformed the planet and helped explain how her carefree approach to life is a protective emotional shell developed over hundreds of years of loneliness.

I don't have kids, so I don't know if this deeper side of Adventure Time gets through to its younger audience, but my guess is that it does. It manages to present more complex ideas in a simple, straightforward format, like the best animated children's entertainment always does, and mix it in with monster-fighting and fart jokes without ever seeming tonally off. It helps that the show is set in a magical world where any plot twist or wacky new location is easily explained away. That's why television intended for youngsters (but written by smart people) so often connects with a larger audience—there's no need to conform to any status quo or traditional notions of realism, and that almost automatically makes for exciting television.

Among the things that have happened this season: Finn discovered a set of living action figures that looked like him and his friends and started toying with them romantically, like a real-life version of The Sims, before realizing their sentience. In another episode, Finn ventured into a pillow fort and lived a whole life, through to old age, although it was all seemingly a dream (but the show really made you feel that life in 11 minutes). In another, a sentient glass of root beer gets obsessed with a threat on Princess Bubblegum's life and jeopardizes his marriage to prove his paranoia right.

Season five ended last night with Finn completing the bucket list of his deceased friend Billy, a fellow adventurer who was killed off last season, and finally conquering his fear of swimming, a longtime plot point on the show. As he rested on his back in the water, Billy appeared in the sky and told him his father was still alive, a satisfying cliffhanger to prepare us for season six, which begins in one short month, because animated TV has weird scheduling.

But more than that, it was a lovely, contemplative note to end a tumultuous season on, another signal to this show's devoted audience that there will be no turning back from Adventure Time's growing maturity. Season four ended on a blockbuster cliffhanger, with Finn battling a skull-headed villain and getting stuck in a different dimension. This year, we wrapped with a fifteen-year-old boy staring at the stars and wondering about where he came from and where he's going. It was just as exciting to watch.