This episode revolved around Marceline's ex-boyfriend tricking Finn and Jake into stealing her memory of the break-up so he could continue being a shitty boyfriend to her. At the end, Marceline, Finn and Jake gleefully beat him to death.

Fun times for kids!

He's a vampire too, so he probably didn't die.

There's the intended audience and then there's the audience.

Ash is a wizard, not a vampire.

Well MOST of them at least.

Spoiler Alert:

Finn is actually a comatose boy in the hospital who was hit by the same car that killed his dog Jake. Now he'll spend the rest of his days fighting injustice until his parents pull the plug.

Dude, he's the last surviving human in a post-apocalyptic world. That is seriously 100% canon. No need to muck it up with meta-shit

He may not be the last human. It's still not clear what Susan Strong actually was.

I've always believed that the PHIL FACE (the recurring face of staff member Phil Rynda) is the face of Finn's father, who put him into cryogenic stasis during the apocalypse so that humanity would have a chance at making one last positive impact upon the world. As he died, Finn's dad made a final wish: to be remembered. And in a way, it came true, because whatever force heard his wish found his face hilarious.

Yeah, sorry to be a downer but Adventure Time is actually the hallucinations of a girl child prostitute. It's the place she goes when the bad men do things she doesn't want to remember. There, she can be anything, so she chooses to be the strong boy her parents that sold her really wanted. There, she has the power to change the world. In Adventure Time, the dead can live on, like Marceline, who was in reality raped and strangled to death at the ripe old age of 14. She also has the best friend she'll ever know, her imaginary friend Jake, who would never let anyone bring her harm. Sometimes the bad people make their way into her imaginary world, like her pimp, The Ice King, but in her world, she can always beat them up. In her world, the Ice King is her bitch.

No, you're thinking of Suckerpunch.

I am secretly hoping that if this show gets a proper ending, it really will just be the imagination of a boy playing with his pet dog.

And of course a few years later, Finn's dad showed up.

He wasn't a nice man.