Attack on Titan has been steadily heading for its grand finale, and the final arc of the series has without a doubt been the most intense in the series thus far. The manga has been building the pieces of Eren's villainous turn for several chapters now, and the latest release has tipped the scales completely as he has declared war on the entire world and is now threatening to eradicate all non-Eldian life. This has shaken Mikasa to her core, and she's beginning to wonder when Eren got this way.
But as she begins to think back to when Eren first started showing this new side to his personality, Mikasa starts to wonder if whether or not he was like that all along. This brings her to a turning point in which she remembers when she almost made a notable confession to him.
Chapter 123 sees Eren awaken all of the sleeping Titans in the walls, and Mikasa and Armin are trying to make sense of what he's doing, and she thinks back to when they first set foot in Marley for reconnaissance. When she and Eren have a moment together, he asks why Mikasa cares for him. She stutters for a moment, but he presses further.
He wonders if she cares for him because he once saved her when they were kids, or if she thinks of him as family. When asked what Eren is to her, Mikasa pauses for a moment and nearly answers "We're family" but is cut off mid-sentence when the others catch up to them. It's here that Mikasa nearly had a huge confession that might have changed the course of things, but it's not as cut and dry as that.
In a previous chapter Eren tried to cut her out completely by coldly telling her that he doesn't care for her, and her protecting of him was due to her Ackerman blood reacting to his Titan power. He even went as far as calling her a slave. Then in a later chapter, Eren revealed that this power allowed him to see into the future and even interact with the past to make that future happen. So even if Mikasa was successfully able to confess whatever she's feeling to him, Eren most likely already knew.
As this realization hits her, she slowly begins to realize that Eren has probably been like this through their entire lives together. No matter how she feels about him, he's been aiming for this path for as long as he's been with her. Nothing she can say or do would change his mind, and nothing anyone can do will really have any impact anymore as now Eren vows to destroy the entire world.
Attack on Titan was originally created by Hajime Isayama for Kodansha's Bessatsu Shonen Magazine in 2009. It's set in a world where the last remnants of humanity live within a walled city in order to escape the danger of the Titans, a race of giants monsters that eats humans. The lead character, Eren Yeager, ends up joining the military with his two childhood friends Mikasa and Armin after the Titans break through the wall and attack his hometown. Now Eren, Mikasa, and Armin must survive in a world where they not only have the Titans to fear, but the very humans they are trying to save. You can currently find the series streaming on Crunchyroll and Funimation.