WARNING: The following article contains spoilers for Attack on Titan: The Final Season Episode 17 "Judgment," now streaming on Crunchyroll.
One of Attack on Titan's most crucial story elements has finally been explicitly introduced in the anime. The element in question is what Zeke referred to as 'the Paths' in the latest episode. It's not the first time the Paths have been shown or mentioned in the show. It's simply the first time that an official name has been given to it.
The Paths were first shown during Ymir's backstory flashback during Season 2. It wasn't mentioned again until the penultimate episode of Season 3 when Eren Kruger explained it to Grisha to the best of his ability in Eren Yeager's memories. Tom Ksaver, the previous wielder of the Beast Titan, most recently explained what he knew about it in Zeke's backstory flashback in Episode 15 of the Final Season.
When Ymir was shown in the Paths in Season 2, viewers had no idea what it was and clearly, she didn't either since no explanation was offered. It simply looked like a beautiful visual flair that didn't mean anything. Fans didn't think much of it at the time and it was a long while before it was seen again. Of course, everything means something in Attack on Titan.
Reiner, Bertolt, and Zeke used to say that they needed to retrieve the Coordinate, which is why they wanted to capture Eren. It was later revealed that the Coordinate is essentially another name for the Founding Titan. The Founding Titan and the Paths go hand in hand. Eren Kruger explained that every single Subject of Ymir (Eldians) is connected to the Coordinate. The blood and bones that form a Titan, memories, and thoughts are all sent through the Paths.
All the Paths cross at a single Coordinate which basically granted the Founding Titan the ability to control all Subjects of Ymir. This is how the Eldians' memories were erased and manipulated hundreds of years ago. It's the reason why the people of Paradis believed that life within the Walls was all there was to the entire world. Marley was able to write the history of Titans however they pleased since the Eldians wouldn't know what was true from what was false. This all changed once Grisha's memories finally opened up to Eren.
Manipulating the minds of Subjects of Ymir isn't all the Paths allow the Founding Titan to do. Tom Ksaver revealed that it can literally change the anatomy of their bodies as well. He discovered through his own memories and Titan research that a terrible pandemic devastated the population around 600 years ago. The disease suddenly vanished from the Eldian Empire when the king at the time used the Founding Titan to alter how their bodies work.
That implies that there's no limit to how much control the wielder of the Founding Titan holds over the Subjects of Ymir through the Paths. Zeke came up with his euthanization plan when he learned this from Ksaver. Zeke intends to use the Founding Titan to alter the anatomy of all Eldians, making it so that they can no longer have children. His stance is that this will save the world from the terror of Titans since Eldians would gradually and peacefully be wiped out. He also believes this is what's best for Eldians because of the suffering they've faced for centuries in the forms of racism, prejudice, and oppression.
Another interesting thing about the Paths is the way Zeke was completely healed. He had his entire body below his chest was blown off by a Thunder Spear at the end of Episode 15 of this season. He was in such a terrible state that he genuinely thought he was going to die. He was picked up by a random Titan and bizarrely placed inside its stomach. He somehow ended up in the Paths where his body was rebuilt by a mysterious little girl. His experience was that it felt like years passed by but at the same time it felt like an instant.
Considering all that's known of the Founding Titan and the Paths, it's no wonder Paradis and Marley are fighting a desperate war over it. Whether it's the Rumbling, the euthanization plan, or something else altogether, everything depends on the Paths. Eren is the wielder of the Founding Titan and therefore the only one who can actually use its abilities. However, Zeke having royal blood makes him the key to unlocking its power. Nonetheless, the fates of every Subject of Ymir and the entire world are in Eren's hands unless Marley actually succeeds in stealing it from him.
