Attack on Titan season 3 ended with an episode that basically soft-reboots the entire premise of the show, with the major reveal of what the world beyond the Walls was really about. The secrets of the world that were revealed didn't just change the nation of Paradis Island, but also had a serious effect on series protagonist Eren Yeager.
As you can see below in the comparison photos, the version of Eren we see a the end of Attack on Titan season 3 is vastly different than the one who started - and leagues away from the boy we met at the start of the series:
Eren has changed pic.twitter.com/I7l67UbiyK— Attack on Titan Wiki (@AoTWiki) July 1, 2019
There is a time-jump that takes place in the Attack on Titan season 3 finale (it's approximately one year), but it's not time that has changed Eren so drastically - it's experience. More to the point, Eren's connection to the Coordinate and Attack Titans allows him to see his father Grisha's experiences, as well as those of Eren Kruger, The Owl. Eren's shared memories with his predecessors in the Eldian Restoration movement have vastly altered Eren's perceptions of the world and his own history, while the Titan mind connection has opened up his awareness of his power, and how to use them.
One of the last scenes of the season 3 finale, "Beyond the Walls" sees the Survey Corps riding to the end of the Walls to finally discover the ocean. Along the way, they group encounters a malformed Titan that's seemingly dormant. While the rest of the scouts are nervous, Eren walks right up to the beast and places his hand on it, and instantly reads the history of the host, who is yet another Eldian dragged up on the Walls and transformed into a Pure Titan.
At the end of season 3, Eren is weighted down by the realization that his long dream of the world outside the Walls is only going to become a nightmare of bloodshed and war with Paradis Island's enemies in Marley. And it's up to Eren alone to carry the weight of the Coordinate Titan - as well as the secret of how Historia may hold the key to unlocking the Coordinate Titan's true power.0comments
Rest assured (and as manga fans know), when Attack on Titan returns for season 4, there will be a very different Eren Yeager leading it.
Attack on Titan season 3 part 2 is now streaming weekly on Hulu, Funimation and Crunchy Roll.