WARNING: The following contains spoilers for Attack on Titan Season 4, Episode 28, "The Dawn of Humanity," now streaming on Funimation, Hulu and Crunchyroll.
Despite his newfound status as Attack on Titan's ultimate antagonist, Eren Jaeger is not -- and never has been -- a clichéd mustache-twirling evil-doer. Eren has doubts and vulnerability just like anyone else, and "The Dawn of Humanity" revealed that Eren once laid himself bare to the one person he's never wanted to feel weaker than, his foster sister Mikasa Ackerman. It's always been fairly evident that Mikasa has stronger, more romantic feelings for Eren and before he went undercover in Marley, he asked her what she felt for him. Fast forward to the terror of the Rumbling, and Mikasa is now wondering if all of this could've been prevented if she'd answered Eren's question differently.
Although Eren is now carrying out the Rumbling without remorse, a flashback to the Scouts' first excursion to Marley revealed he has been looking for a way out of the dark future he saw when he kissed Historia's hand in Season 3. When Eren looked upon the refugee camp and said nothing has happened "yet," it became clear that he even saw the impact of the Rumbling four years ago. Eren and Mikasa had never discussed the way they feel about each other before this point, giving the impression that he was truly desperate for any indication of another option besides destroying the world.
Eren's question for Mikasa, "What am I to you?" caught her off guard and she answered quickly, seemingly in embarrassment, that he's family. This didn't seem to be the answer Eren was hoping for, as he expressed disappointment when the rest of their friends arrived -- meaning that he and Mikasa would not be able to continue their conversation. Mikasa's blushing embarrassment at the question (along with everything else she's ever said and done to/for Eren) made it clear that she has strong romantic feelings for him. Given that he asked at all and seemed disappointed by her answer, this was Attack on Titan's first indication that Eren may return these feelings.
Knowing he would one day unleash the Rumbling and slaughter far more innocents than enemies would surely make Eren feel like a monster. In his lowest moment, before he fully committed to the future he saw, he turned to the only person who's always supported him in search of validation and did not find it -- at least not the way he needed it. The day after Eren asked Mikasa this question was the day he lost all hope for a peaceful solution and abandoned his friends to infiltrate Marley. Now that the Rumbling is moving forward in full force, Mikasa is beginning to wonder if Eren would have done this if she'd been honest with him.
Who knows what Eren would have done if Mikasa had told him how she truly feels about him? Maybe it would have added to his sorrow that he would inevitably break her heart by being forced to turn against her. Perhaps it would have given him hope to keep searching for a peaceful solution with Mikasa at his side. It's possible Eren was just looking for something to hold onto before he was forced to destroy the world -- or maybe he would have given up everything just to be with Mikasa. All these questions and more are surely fighting for supremacy in Mikasa's head as she considers the possibility that she could have saved the world if she'd just told Eren that she loves him.
Eren's question for Mikasa is the most vulnerable he's ever allowed himself to be with anyone, and his feelings for her may indeed make it possible for Mikasa to talk him down if they ever catch up to him. As it stands, the last conversation the two have had was when Eren told her he's always hated her, which was a far cry from his previous question about how she feels about him.
Could it be that the world's greatest enemy is flattening the Earth because of a broken heart? There are a lot of things that many characters in Attack on Titan would go back and do differently, but the answer Mikasa gave Eren might be the one mistake that doomed the world more than anything else.
