"Eren and Mikasa" is Inherently Toxic - and Nonexistent!
I normally don’t care for debating about anything having to do with character motivations with the ending, given there’s more than enough objective plotholes and retcons to make the ending undeniably awful, but there’s one major exception to that - the idea of Eren liking Mikasa, or of Mikasa’s obsession with Eren being anything but toxic and pitiful. The reason for that is two things - one, it’s so easy to completely tear that idea apart that it almost destroys the credibility of anyone who genuinely argues for it, and two, their dynamic (or lack thereof) was purposefully written to be that way! First of all, before tearing apart the idea of Eren liking Mikasa, let’s break down the idea of Mikasa’s obsession with Eren being “love”.
The first thing one probably can figure out about it is that it’s not really “love” that she had; she was never once shown to actually love anything about him. Mikasa has proven time and time again that she doesn't care for the real Eren, idolizing a version of him that doesn't exist, and worst of all doesn't even try to understand him or what he wants. Eren not once in the series has a single personal, real conversation with Mikasa, like he did quite often with Armin and other characters. Even Eren's “rival” Jean proved to understand and relate to Eren better than Mikasa ever did, especially through Season 4. Or really, all of Eren’s friends understood Eren better than Mikasa ever did - her failure to understand who Eren is as a person was written to be so extreme, it was used as comedic relief!
Or, let’s look at their conversation about Eren in Chapter 108:
As you probably remember, this comes after Mikasa trying to argue with them that Eren cares about “his friends more than anything”, ending with Connie saying this, and Mikasa not responding. There’s a bit more to this than you might first realize, though. Connie asks why Eren laughed, and she stays silent; she’s clueless. This detail was put in to emphasize how Mikasa doesn’t understand Eren at all, let alone emotionally; how do I know this? Because if you didn’t make the connection, Mikasa’s seen him break down laughing before:
She’d already seen this same thing before, the same situation of him breaking down laughing as a coping mechanism in an identical scenario, yet she didn’t understand it - or him - at all.
And, worst of all, her obsession with Eren isn’t built on anything that genuine love is whatsoever, instead being built upon the infatuation Mikasa has with Eren for saving her as a child, and nothing else - or putting it more professionally, that Eren became the last family she had left, all she had to cling to and all she had to protect. She doesn't like anything about Eren, she doesn't understand anything about Eren, and only "likes" him for completely superficial reasons - or if there is anything she likes about Eren, we never get to see it.
The point? That it’s a fundamental part of the story that their “relationship” could never work, even if Eren ever reciprocated anything back (which isn’t even the case as I’ll explain [even though I shouldn’t have to] in a second), and that Mikasa never actually loved him, at least in a healthy way. The show choosing to portray that dynamic as love rather than an obsession throughout the final arc is one of the most tonally dissonant parts of the ending, and shows Isayama's utter failure at recognizing the toxicity of this on Mikasa's part - or rather, his purposeful ignoring of his own story and established plot elements in order to “please the fans”, as I’ll explain in a second.
Next, let’s break down what Mikasa’s obsession with Eren was supposed to be and why it mattered in the story. Isayama’s talked about this quite a bit, so this should be pretty easy.
First of all, a lot of it has to due with Eren being all the family she has left - you know what, rather than explain myself, I’ll let Isayama do the talking:
"As a girl, Mikasa was adopted by the Yeager family. She loved Eren as a brother (family in original text), and refused to let anything get in the way of protecting him." (Inside & Outside Guidebook, 2013)
"At that time Eren allowed her to discover renewed value again, like that of a newborn bird's first glimpse at a grown one - it was that kind of admiration and trust. Thus, she swore to follow Eren. However, Eren was actually even more childish than Mikasa. As his committed caretaker, she also thinks at times, "Ay, what a worrisome child." (Guidebook ANSWERS, 2016)
"The Yeagers raised Mikasa, and as someone who has lost all of her blood relatives, they are her only family. After losing Grisha and Carla, Mikasa takes up her blades in order to protect Eren, the only one she has left."(Shingeki no Kyojin Character Encyclopedia, 2017)
"The scarf that Eren gave to Mikasa as a present when she was adopted by the Yeagers is one of her prized possessions. Mikasa most likely sees it as an item that symbolizes the beginning other bond with her new family." (Shingeki no Kyojin Character Encyclopedia, 2017)
(MINOR BERSERK SPOILERS FROM HERE TO NEXT LINE OF DASHES)
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That’s the gist of the “family” part of it. And for the obsession part, Isayama told us something very interesting (and constantly overlooked/unknown). From Gekkan Shingeki no Kyojin Volume 3,
“There are some parts of Mikasa that are unrefined, yet on the other hand, she has a brave personality. I think these are influenced from the heroine of Berserk, Casca. At that time while drawing, I didn’t realize it - but after a while, I realized that Mikasa resembles Casca.”
When you break it down, Mikasa’s dynamic with Eren is nearly identical to that of Casca’s dynamic with Griffith (pre-Eclipse of course), so much so that it’s almost undeniable that there was influence from Berserk, not just for the dynamic but for events in the story as well.
If you think this is a stretch, stay with me - it gets eerily similar.
How do Casca and Griffith meet? Casca is about to be [I’m sure you can guess], when Griffith shows up and saves her by giving her a blade and telling her to fight. How do Mikasa and Eren meet? Mikasa is captured by traffickers and going to be [I’m sure you remember the trafficker’s conversation], when Eren shows up, gives her a blade and tells her to fight. What happens next? Casca/Mikasa picks up the blade, protects herself, and then:
Griffith/Eren wraps the Scarf/Blanket around her, and she remarks about its warmth - physical, sure, but referring to it in an emotional sense, with bittersweet tears as she looks at Griffith/Eren, a perfect savior in her eyes. Even the panel itself seems to have been directly copied (I prefer to use inspired most of the time but it’s literally the same), it’s genuinely the same exact shot (and context) in nearly all aspects, haha. But more importantly, what is their dynamic after this? Spoiler alert: it continues on the same exact path, same dynamic, with the same development - until it wasn’t.
Casca obsesses over Griffith, he reciprocates nothing. Mikasa obsesses over Eren, he reciprocates nothing. Mikasa acts as Eren's Sword, his protector, Casca acts as Griffith's Sword, his protector, and both lament about the same problem - he always goes away from them, out of reach.
Later on, Griffith starts to drift away from them (Band of the Hawk), and Casca reflects on her understanding of Griffith - or more so, her lack of understanding of Griffith. Later on, Eren starts to drift away from them (Scouts), and Mikasa reflects on her understanding of Eren - or more so, her lack of understanding of Eren.
What triggered these events? Berserk, it was Casca seeing Griffith after the 10 year old boy was killed, as he looked upon the boy’s corpse and talked about the boy dying for his dream. AOT, it was Mikasa seeing Eren have his laughing breakdown following the death of Sasha, who died for his dream (more so that was the point where she locked in to realizing something was up, but it was generally just post-timeskip as a whole). The panels I put for that don’t show this too well, but I didn’t want to clog this up with too many, since it takes some more to fully show this parallel here alone. Regardless, what happens here is the same; she realizes the Eren/Griffith she’s been seeing all those years, her angelic savior, isn’t an angelic savior, and begins to reflect on her lack of understanding of who he really is.
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Here, though, we’re going to need to do something different. We’re going to take a look into what Isayama said was going to happen, and what he said about these characters, and then we’ll look at what did happen.
The most important interview for that is this:
Guidebook ANSWERS, 2016: “Mikasa’s growth probably involves separation from Eren. By separation, I mean she might be able to return to that ordinary girl that she used to be in childhood …. I think it is pitiful if Mikasa’s life is only about staying together with Eren. However to Mikasa, it is a wonderful thing to be with Eren forever. Combining what I’ve said, if I were to draw the separation of Eren and Mikasa, I feel like my portrayal likely won’t be satisfactory for readers, because Mikasa would have to endure the strain of being stuck between Eren and Armin.”
Why does this matter? Well, let’s look at what happened with Casca from the last point I left off with:
(LAST SECTION OF BERSERK SPOILERS, but spoilered this time!) Edit: I don't know how to spoiler images, lol. Go to the next line of dashes to skip past it.
After that point where Casca started to think about how well she understood Griffith, she began to drift away from him, as I’m sure you know becoming close to Guts and overcoming the false vision of Griffith she had in her head. Did she still care about him? Yeah, of course, but not how she did before, as she grew as a character and (presumably) began to recognize that what she had before was one-sided and toxic, as well as her relationship with Guts developing through that whole time.
And for those of you who might, for some reason, try to argue that’s not the case, Judea describes her and Eren/Griffith’s dynamic perfectly:
Replace the names, Casca and Griffith to Eren and Mikasa, and every detail of it describes their dynamic perfectly. I bet you could copy and paste his speech with switched names and nobody could even tell it was referring to something else.
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Berserk Spoilers over!
Now it should be clear why exactly Isayama thinks her obsession with Eren is “pitiful”, yet also says Mikasa thinks it would be a wonderful thing to stay with Eren forever - she worships him, and in an unhealthy way loves him, but it’s detrimental to her own being and own happiness given it could never be reciprocated, since the person in her mind that she worships doesn’t really exist.
But if we followed that arc Casca and Mikasa were upon, it should be pretty obvious what happened... at the very end, Isayama went off the path he described in that interview - of her returning to that normal childhood girl, separation from Eren - and while that last sentence, her choosing between Eren and Armin, was somewhat kept with what we got, the rest was obliterated and everything that defined her character’s biggest obstacle and biggest trait was ruined. Want to see what I mean? Let's switch the places of Casca and Mikasa, and see how absurdly awful her (Casca’s) conclusion becomes when made like Mikasa’s:
Firstly, let’s change the Eclipse so it consumes 80% of the world and 4 members of the Band of the Hawk, but leaves the rest alive. Also, everything Griffith does as Femto… I’m sure you can guess what, doesn’t happen. Casca and the Bank of the Hawk manage to defeat Griffith and stop the Eclipse, and Casca beheads him, kissing his decapitated head. He uses the powers of the Behelit to create a dream world where him and Casca spend four years together, where him and Casca ran away together! Afterwards, he uses that same power to talk to Guts, and we find out Griffith “kept moving forward” that whole time to see if Casca would kill him or not, to see the outcome of her choice. He also admits that he loves her, and had loved her that whole time! After all of that, Casca keeps his decapitated head, walks across a barren wasteland continent and swims across the ocean to an island with it, where she marries Judea and has a kid with him, but that whole time stays loving Griffith forever and visits his grave constantly until she gets buried next to him as an old woman. In an interview a few years later, Isayuira says he actually intended for Casca and Griffith to kiss during the lake scene, despite it not making sense at all with past interviews and the story itself.
While it's obviously not a perfect comparison, you can see how the conclusion we got doesn’t make sense (and is fairly grotesque) for Mikasa and nearly every aspect of her character. As for why this happened, the easiest answer is probably just that during Isayama’s complete burnout and urge for the story to conclude during the final arc, he chose to “please the fans” (if you think Eremika shipping is bad with Western fans, just know it’s drastically worse with the Japanese audience) and not care about abandoning crucial elements of his story. And given how badly he screwed up other parts of the narrative from 133 onwards (Wall Titans' many plotholes, retconning of Pastor Nick, Falco's Titan for example), what’s a few more major plot elements?
Edit: Someone sent me a pretty great analysis on this subject, but instead of talking about the Casca parallels it describes how Annie was used throughout Season 4 to parallel Mikasa and call out her flaws. It also makes some great points about Armin and Annie, which while I do agree with Titanfolk was rushed, I do like for the reasons stated within it (and liked before, I predicted their relationship way back during Season 3 and will never stop boasting about that). It also has a nice section describing how Eren and Mikasa were written to be fundamentally opposite characters.
At the beginning of this I said I’d tear apart the idea of Eren having romantic interest in Mikasa after her section, but now I’m realizing how long this has gotten. Instead, I’ll make that it’s own post, and link this post in the beginning of it. Thanks for taking the time to read :)