When Adventure Time ended in 2018 with the sublime “Come Along With Me,” fans felt a specific kind of closure. It was bittersweet, hopeful, and final. So when HBO Max announced Adventure Time: Fionna & Cake —a spin-off focused on the gender-swapped versions of Finn and Jake—many assumed we were in for a nostalgic victory lap. A fun, low-stakes romp through a parallel universe.

(Deducting one point only because the musical numbers can’t quite beat “Everything Stays.”)

We find Fionna living in a non-magical, Simon Petrikov-created universe. She works a dead-end job, she’s bored out of her skull, and she desperately longs for the epic adventures she’s read about in Simon’s old fanfic. Cake, meanwhile, is just a normal house cat. The world is grey, mundane, and suffocating.

The series argues that happy endings are a lie we tell children. For adults, endings are just new beginnings that are often less interesting. When Fionna accidentally breaks her universe, she isn’t unleashing chaos—she’s unleashing potential . Danger is re-introduced to a sterile world, and paradoxically, that danger feels like relief. On the surface, Fionna is a reboot of Finn: spunky, sword-wielding, impulsive. But the show actively dismantles that trope. Fionna is not a good hero. She gets her friends killed (temporarily). She ignores warnings. She throws tantrums when reality doesn’t conform to her expectations.

The new series takes a radical step: It makes Fionna and Cake real. But not in a heroic way.