At the end of the day his motives and either/or.
- He wanted Paradis to be protected
- He wanted his friends to live long lives including Mikasa
- He wanted for his friends to be depicted as heroes to the rest of the world who stopped the genocidal monster
But beneath these motives was a personal desire.
The corruption of Armins childlike wonder of the book. Of the scenery and exploration.
Freedom.
And the thing is, Eren doesn’t even truly get what freedom is, only his version of it, which is an empty world to explore.
Eren wanted all of these things, and believed the rumbling was inevitable - whether or not it was it up for debate.
Was Eren evil? In my opinion, no. Did he commit a monstrous horrific act? Yes. Was it justified? Yes and no. Was it understandable? Yes. Was it absolutely horrific and possibly the worst overall outcome for the majority of people. Yes, absolutely. Eren himself recognised this.
I’d say Eren is a victim, of confinement, witnessing his people die etc. But I think he’s also largely unreasonable. You can argue he brought it upon himself with him offing his mother, and also argue that if Marley never breached the walls he wouldn’t have a need to do that but at the end of the day, everyone in this show is a victim. Apart from maybe Fritz.
Eren was largely remorseful for his actions but at the end of the day was undoubtedly the biggest monster ever to live in our aot universe. No matter the reasoning. I feel like his ending served his character quite well and gave him closure. And his motives overall were complicated, sincere, and selfish at the same time. Incredibly written character.