Eren a slave to Past and Future (how I think it'll end)
Attack on titan fandom is huge so I'm sure somebody has said something like this but I'm giving my own take on it. I believe that the series will end with Eren being trapped in a time loop purgatory after taking the place of Ymir. When ever the time comes for Eren to die I think he's just going to end up going back to the beginning. Even if everyone else gets a somewhat decent ending I dont believe Eren will be getting that at least not a lasting one. Now why do I think this? Just look at the first few pages of the first chapter
It starts with some scene of Mikasa bidding him a farewell with her hair a little longer than it is now but shorter than it was in the past. Which tells me the "Mikasa farewell" is a bit farther in the future than where we are right now in the manga. With the bit of black possibly being Eren losing consciousness/ dying. Eren asks Mikasa why her hair is so long when waking up. Telling me the last memory younger Eren had from his former self was the short haired older Mikasa.
Eren talks about having a real long dream and starts crying. Why would Eren be crying? Yeah about all the memories of the past but also even though younger Eren can't remember what all happened. I think it could also be his soul crying, a reminiscent emotion of his former self realizing that he who craved and cared about freedom more than anything else cannot be free and is a slave to his past and his future. And due to his memory loss unknown to him at the moment he has to do it all over again.
A part of me wonders if at some point Eren realizes this but goes through with it anyway because the happiest route that his friends can hope for is a route where he has to end up suffering for the long term. It also makes me think about that scene when him and Armin were arguing and he was calling everybody a slave when Armin called him a slave he was genuinely upset by it. Though we know the reason why he acted like that was to spare them when Armin called him a slave broke character and old Eren slipped out. And the crazy part is Armin didnt even call Eren a slave in the scene but for some reason this how Eren heard it. Maybe because he knows that that's exactly what he is.
I think back to the scene when Eren was talking to himself in the mirror trying to convince himself to keep fighting because of how hopeless he was feeling
When Hange walks in on him and says something interesting that at first you could just take it as a joke or just at face value with the battle and Marley and where we are now but looking back at it I've interpreted it differently and found the fact that it was pointed out to us in the way that it was to mean something, or be more significant than first realized.
"You said "fight, fight" fight what? if you said fight twice? Does that mean it's a round 2 fight?"
It's like a hint to let us know all this stuff around happened and is just happening again or at least that's how I take it.
This scene to at first I had an interpretation of it about Eren wishing there was another way than what he is currently doing with the rumbling but now I feel an even deeper interpation of it. It's not just that Eren wishes there was another way. Deep down he knows there isn't in tested theory and he has no choice but to do the same thing again.
I think this theory would bring things full circle in a pretty fucked up way. But you know attack on Titan is pretty fucked up so it would be fitting. You hate titans turns out you are a Titan, You want freedom, you even manage to free others and end up making a huge change while doing it. But end up becoming a slave yourself for the sake of others, and a slave to the thought of freedom. To the past and the future.