The thing about Shadowbringers is, it's not merely a story that flips the concepts of Light and Dark on their heads and makes us question what heroism and villainy are. It's a story that takes the concepts of fate and destiny and stomps them to death.
It begins with Ardbert back before Stormblood. The Warriors of Light, chosen by the Crystal, fated heroes of the First failed. Their triumph over the Ascians plotting against their world caused its destruction, and when faced with that horror, they fell. They turn into villains to try to save it.
And that fails, too! Doing everything they were supposed to do was the wrong thing, and doing everything they weren't supposed to do was the wrong thing. And in the end, their world is saved by Minfilia -- who is very pointedly not a Destined Hero. Even at the moment that she agrees to go to the First, she's an oracle. Her job is speaking. She does it anyway, and it works.
G'raha back in ARR, following the course of destiny laid out for him by Princess Salina, doing what his bloodline was fated to do, sealed himself inside the Crystal Tower so that it could one day be a beacon of hope. And it worked! When the tower was opened, it absolutely was the embodiment of all of the Eighth Umbral Era's hope. Because the world was dying. That was his destiny. To be the hope left trapped in Pandora's box.
The Ironworks sends him back in time explicitly to defy fate. To make sure that everything that was supposed to happen didn't. But even as he goes about it, G'raha still doesn't fully reject the notion of destiny. The Fated Hero has to be the one to save the First. A destined sacrifice has to be made to save the future.
Throughout Shadowbringers, we see events diverge more and more from how they were supposed to be. Whoever slays a Lightwarden is supposed to become one. Whoever kills Titania is supposed to become the new faery king. Vauthry is supposed to be the hope and salvation of the First. Destiny is being averted, the Eight Umbral Calamity is maybe being forestalled, but there's still this overarching sense of fate. The Warrior of Darkness, long awaited by the First, has come at last to set things right.
She is very literally the embodiment of destiny. Minfilia will return. That's the prophesy, and over and over again it is fulfilled. Until Ryne, who has never been allowed to fulfill her destiny, the first Fated Symbol of Hope kept in a cage, finally reaches Light's Edge and makes her choice. And what she tells Minfilia? "Coming together, providing for one another--that's the only way forward I can see. Since all our heroes are gone, we'll just have to make heroes of ourselves." That is an explicit rejection of the Great Destiny she was promised. We are our own hope. You and all our other great heroes are in the past. Together we have to rise to the occasion.
And with that choice her destiny ends. She ceases to be Minfilia. She no longer has the crystal eyes and blonde hair that marked every one of her past reincarnations. She becomes her own person. She's free of fate.
In some ways the importance of the moment gets buried behind the continuing quest to find and kill all the Lightwardens, but Ryne is the turning point of Shadowbringers.
After that moment, the fated Warrior of Darkness begins to noticeably break. The triumph over the final Lightwarden is fleeting. The noble sacrifice doesn't happen. Ryne intervenes when the Light overtakes you, and your destiny doesn't arrive. We spend all of the Tempest in a liminal state--neither the monster nor the hero but both, in a city that does and does not exist, witnessing scenes of the past that will become the future.
Ryne is the last to fall to Emet-Selch, and when she does, she's the only one who calls out to us. Not to Emet-Selch. She's not trying to argue with or fight him. He's not the real adversary to her. She wants us to fight against what is supposed to happen next.
And because of that, Wol and Ardbert claim control of the narrative. "This is our story." They stop following the plot set out by fate, and from here to the end of the universe, anything can happen.
