Edit: Title was supposed to be, "What I understand about Attack on Titans after 138... and think about 139"

Thinking about everything that' happened in the story. My guess is that Eren saw 'some' of what was happening. The war, bloodshed, etc. He choose to become a devil for one simple reason - https://youtu.be/JvZZ_pwDsx0?t=38

I think, in the end, he choose to fight on as the devil. Not as a martyr, a savior, or a slave. But as a perpetrator. Someone that could crystalize and catalyze the horrors that both Marley and the old Eldian Empire had committed. And act as the central focal point for everyone's hatred, prejudice, and anger.

The world wouldn't hate Eldians or Marleyian. Just the man that stole the Founding Titan away from Marley. And betrayed his own friends and family. Made an extremist by Marley, sure. But sacrifice many, many friends and family for his own war against the world.

And this, I feel, is true...

I know very little about Norse Mythology. And would love someone more knowledgeable to correct me. But I truly believe Eren is this stories representation Surtr.

My understanding is that Surtr was a soldier and a sentry at the edge of his kingdom. He eventually became the first line of defense against foreign invaders, Aesir gods, etc. And Surtr always fought with a flaming sword. Burning everything the sword touched.

One day Surtr retreaded from the front lines. And went to work forging and reforging his flaming sword. Hardening, sharpening, and heating it. It's said in legend that Surtr forsaw he end. That he saw Ragnarok and he role he played. And had accepted his fate willingly.

When he was ready he took the sword and his kin. And waged war against the Aesir (and Vannir I think). Unleashing the mighty Fenrir on Odin (or maybe Fenrir broke free, I'm not sure on this part). Regardless, Fenrir killed Oden and many, many, many Aesir gods, lands, and kingdoms. The depictions very, but my personal favorite is that Fenrir swallowed the land, the sea, and sky before Sire strikes the beast.

Thor killing Jormungandr, but only able to live moments afterwards. The wound from Jormungandr, and the poison it released, killing Thor. And Surtr burning away the rest of the world.

In the end, all that's left of the old world are two people - a man and a woman.

Thinking about Chapter 138 with this in mind, the story suddenly makes a bit more sense:

• Eren is the Surtr equivalent. A man who tried to fight on the front line. Somehow saw or envisioned his future... and excepted that he was the villain.

• Eren's Founding Titan Form... It's Fenrir. Or I think it's Fenrir. A being capable of devouring the land, sea, sky, and everything in its wake.

• I think Zeke is the Loki equivalent. Zeke is directly responsible for spawning so many horrific Titan abominations that directly respond and listen to him. Even Jormungandr, if memory serves, is one of his children. And that's damn important.

• The warm that spawned from erens neck is a Jormungandr equivalent - aka The World Serpent. A beast/serpet/wyrm that poisoned the bodies of Eldians.

• I feel Reiner is the Thor equivalent now. "Thor! So mighty, so strong... he ruins everything."

• That leaves Mikasa and Armin. There was a point-in-time I would have said Armin was the 'Odin' equivalent. And Mikasa was the Freyja equivalent... now I'm not so sure...

Two final things that I think will make sense in the very end of chapter 139. Is these 2 scenes:

https://youtu.be/JvZZ_pwDsx0?t=38

https://youtu.be/k45gWDo7qLQ?t=5

Eren Kruger, and Eren Yager. Both speaking in these 2 scenes... but I have a tinfoil hat theory. Eren Yager, in the 2nd shot... was never talking to his friends.

My theory boils down to modern medicine - yep :) The worm, and the fluid it released, is something that affects Eldians. How fitting would it be if it wasn't war that saved Eldians. It wasn't freeing Yimir that saves Paradise...

But a shot. A vaccination. That worm's fluid is a part of every Eldian. Magic isn't going to remove it. Unless you followed Zeke's idea - Eldians, 40 years later, can become Titans.

But what if, 40 years later, science has advanced to the point that the Titan Transformation can be inoculated. That a shot can vaccinate you from ever becoming a Titan.

The final scene, I believe, was never Eren holding his child. But an Eldian man 40 years in the future giving a baby the very first anti-titan-transformation vaccine. Freeing her from a life of fear, of worry of becoming a Titan. She's free of the curse. Not from magic. Not from war. But from Medicine and human endeavor.

Finn.

Edit 2: The 40 year timeskip makes too much sense to me the more I think about it.

Reiner is fighting a worm that turns Eldians into Titans. This is the first true depiction of the 'source' of titan power the world would have. And would be a way for the world to study the effects of this creature on Eldians. Ultimately leading to a cure instead of war/genocide.

Reiner, Eren, the Survery Corp, the Warriors, Marley, and Eldia would have been taught in history books by this point. With those that lived through the war getting older and older. And with very little changing for them until this 'vaccine' is distributed to Eldians.

If I'm right. Then the Authors 'leak' of the final page was red-herring the entire time. It was never Erens kid. It was just some random kid.