thinking about Finn and Fern and how The Death of Legacy was essential to their story's resolution
Legacy is a repeated theme throughout the series—legacy, destiny, our ability to change and/or uphold those, whether or not it is our responsibility to do so, even when that legacy or destiny directly conflicts with our morality.
Each character confronts (and usually kills) the legacy assigned to them in one way or another throughout the series: Marceline rebels against Abadeer, PB relinquishes her place of power, King of Ooo has his own fall from grace, BMO confronts and kills AMO, NEPTR refuses to succumb to evil, Cinnamon Bun escapes the "dumb clutz" persona he held in the Candy Kingdom, Flame Princess subverts every expectation held for her and shows an immense capacity for kindness and forgiveness when expected to lash out or become evil, Ice King goes from "evil freak" to "irritable weird old man who cares about people a lot" even in spite of the fact that the Crown was imposing aggression onto him, Gunther/Orgalorg throws away another chance at unfathomable intergalactic power for a chance at the love Ice King was always searching for, Betty became a chaos god rather than accepting the fate of Simon's death because of her own summoning ritual, Jake sacrificed his role as an active father to continue raising Finn when he realized who needed him more immediately, and perhaps the biggest example of this is Sweet P, who is the Lich reborn.
And all of this is not even touching Finn or Fern.
Finn and Fern actually share a legacy of a well-known and generally respected hero (though some of that trust was damaged after the episode, "The Tower," when said tower collapsed onto the Candy Kingdom and, "lotsa folks got squished"). They share the legacy of "The last human in all of Ooo," and as "Son of Martin Mertins and Minerva Campbell," and as "Son of Margaret and Joshua," and as "Little brother to Jake the Dog and Jermaine," and as "Father of NEPTR," and as "Flame Princess' ex boyfriend," and as so much more.
but Fern has this additional legacy attached to him, this separate history where his timeline and Finn's diverge. He has the legacy of "The Sacrifice that brought back Prismo"—a sacrifice that he did not consent to making, by the way. He's got the legacy of "Finn Sword," protecting the version of himself who sacrificed him and separated him from his own Jake, who was also sacrificed for Prismo's sake. And then he has the legacy of the Grass Wizard forcefully imposed on him, this legacy of the Grass Sword's curse, of evil.
And then Finn imposes the legacy of "brother" onto him. forces him back into the old shoes of "Finn the Human, Hero of Ooo," when he's still trying to figure out what he even is now. What all of it means. It's like with the Jiggler all over again, where Finn refuses to address the underlying issue of the fact that there is no space for Fern here.
And Finn never realizes, the self-sacrificial guy that he is, that Fern is seeing all of this for the first time, is finally realizing how Jermaine must feel, because when it comes to Finn and Jake and the bond that they share, there's not really any room for anyone else. but Fern is also only a sixteen-year-old boy—why does Finn deserve to be loved and cared for by his big brother, but Fern doesn't anymore? Why is Finn the only one offering him comfort? Oh. Right. Because he feels like Fern is "his responsibility."
So Fern already feels out of place, and he recognizes that, unless Finn is gone, he will never have Jake again. And he decides that, in order to step into "Finn the Human, brother of Jake the Dog," maybe the legacy of "Finn the Human, Hero to All in Need," may have to fall.
And then we have Finn, who embodies kindness and compassion, who refuses to kill Fern, but ends up doing it, anyway. Who, because he couldn't save this version of himself, feels he has lost the legacy, "Protector," has failed to uphold the legacy of, "Brother," has maybe even lost "Hero," in the scramble.
