You thought Mikasa was a complex character? Hahahaha! Eren is worse. Yes, if you still think that Eren is just an angry guy who wants to kill all the titans, you're wrong. Totally wrong.

That's why analyzing him is going to be hard (and pretty long), and some of my arguments may be just one of the possible interpretations... You may not agree with my own interpretation and my opinion. Again, give me your opinion about that, this is important for me, even more in this part 🙂

To make things clearer, I will start like in Mikasa's part: "Does Eren consider Mikasa as his sister?". It won't be very long because there are no ambiguities: Eren never referred to Mikasa as family. (and neither do all the other characters...). Moreover, when he is angry because she overprotects him, he says "I'm not your little brother nor your kid!"

That's all. That's my only arguments, but I think it's enough because on the other side, there are no arguments proofing that Eren sees Mikasa as his sister. (Tell me if you do, but I don't see any)

Now, let's try to find out what kind or relationship Eren has with Mikasa, what kind of feelings he has for her.
I heard some people say that Eren doesn't deserve her, he is not a good person, he just thinks about killing titans, etc. First, the idea of ​​having to deserve someone is stupid, the "someone" is the only person who can say if he deserves it or not. And honestly, if you think that Eren is a jerk or something like that, you're deaf and blind. Let me remind some things he did for his friends:
He saved Mikasa from three criminals, risking his own life for a a stranger. (But I'll talk about it again later)

He was always here to defend Armin from the "bullies".

He stopped talking about his dream to go outside the walls for several years for the sole purpose of dissuading Armin from entering the Survey Corps. Yes, it's subtle, but it was a way to protect him. Note that Eren can care about someone without showing it explicitly...

He also tried to convince Mikasa to enter the Military Police instead of following him in the Survey Corps. Although he has a bad opinion about the Military Police, he knows it's safer for her. Also, read Mikasa's answer ❤

He gave his life to save Armin from the "Santa" Titan. Of course in the end he did not die, but he didn't know that he would survive. He was really ready to sacrifice himself.

Although Eren is always angry and obsessed with his revenge, he always cared about the others. Everybody. Armin, Mikasa, but also all the soldiers dying.

So... "Eren doesn't care about Mikasa"
This is definitely wrong. I mean, Mikasa is so often protecting Eren and showing him her feelings that we forget what he did for her: Every time Mikasa needed help, he was there for her. He cares about all the people, but especially Mikasa. Maybe you had not noticed that, but in every (rare) situation where Mikasa was the one who needed to be protected, he did protect her.

Obviously the first time was when he met her. He killed two men to save her although he didn't even know her, and he succeeded to activate her power by telling her to fight. "If you win, you live. If you lose, you die. You can't win if you don't fight." In chapter 50/Episode 37, when Mikasa thanks him for showing her how to live her life, I think she was talking about this famous speech that changed her mind. And more than saving her, he gave her a home. By home, I don't only mean a house. Actually, Mikasa's home wasn't really the Jäger's house, but Eren himself. Remember that she said that she still has someplace she can return to. This "someplace" is basically Eren's side.

On that day, all of what he did for her was symbolized in one single gesture: Eren giving Mikasa his scarf. This is the origin of the strong symbolism of the scarf, and also why it represents the relationship between Eren and Mikasa.

Someone told me that Eren didn't give his scarf for this reason. Yeah, of course he didn't...
Because the gesture of Eren giving her his scarf isn't valuable in itself but by the meaning that Mikasa gave to it. For Mikasa, the scarf stands for everything he did for her, and not only wrapping her in his scarf because it's nothing compared to the other things. It's Mikasa and only her that kept the scarf because for her it represents what Eren did.
However, the fact that Mikasa gave a meaning to something which wasn't that meaningful originally doesn't attenuates the importance of what Eren did...
It's obvious that Eren didn't intend to give the scarf this meaning, but for Mikasa it was the icing on the cake, and that's why the scarf now has this meaning.

Let me explain it quickly: Eren saved her, and then gave his scarf to her. Mikasa kept it to remember that he saved her. Of course that was not the point of Eren's gesture... But that doesn't change the fact that he saved her.

Also, Eren wrapped her in his scarf because she was cold. Mikasa kept it because his gesture was something beautiful in this cruel world. Again, that was not Eren's intention but that doesn't change the fact that his gesture was beautiful.

Another example of Eren protecting Mikasa is the Courtroom scene. He accepted to be treated like a monster but refused that she was. Again, he cares about her without saying it explicitly.

He defended her from the titan in episode 7, but maybe he was just at the right place at the right moment, I don't know... He didn't even look at her 😂. So, coincidence or not? You decide...

Finally, episode 37/chapter 50 (yes, again, but so many things happened between Eren and Mikasa here...). Mikasa thanked him, etc. And then, he stood up to fight the titan. Alone, with his little fists. 😆

It means sooo much... He said that he would wrap Mikasa in his scarf again, as many times as she wants. Obviously, that doesn't just mean giving her a scarf but that he would protect her again, as many times as he needs to. Like the first time he wrapped her up in it, he would be ready kill again to protect her. Regardless of the enemy, even if it's a titan, even if he doesn't have any weapon. If he had to do it again, he would do it again. That proves that he understood the meaning that Mikasa gave to the scarf, which is important because it means that he also understand at least a part of Mikasa's feelings for him...
Then he also remembered his mother telling him to protect Mikasa, "for once" (killing for her is not enough lol). We saw in Eren's eyes that he took it really seriously. And he proofed it: since this day, which was just a normal day in his childhood, he has not forgotten what her mother told him, and he remembered it when decided to protect her.

However... it's true that Eren was yelling at Mikasa, and he was sometimes truly mean, headbutting her and rejecting her. He acts like a jerk. Yes, that is true. No... Actually, it was true. I mean... Yes, are you still stuck in season 1? There has been an evolution in Eren's character...

By the way, did you know that Isayama has been influenced by the anime for Eren's character? He has been impressed by the voice acting, and he said that he helped him to understand Eren. He wasn't planning any evolution in his personality, but in the end he did it, realizing the deep feelings Eren could have. What is important is that throughout the story, he starts to accept his weakness. Here is an analysis of Eren's character written by a fan, I totally agree with him:
https://www.reddit.com/r/ShingekiNoKyojin/comments/657gp6/manga_spoilersangry_anime_eren_is_the_better/
(you can't click, just copy and paste)

Also, Hajime Isayama requested for Eren to be "worse" in anime. He wanted him to look more angry and useless in anime. (Sorry I didn't find the original source of this information but I saw it several times, so I guess it's true...) I personnally think that it's a way to mark the difference between himself at the beginning and himself after he evolved.

Again, let's have a look on episode 37/chapter 50. If Mikasa was really going to kiss him, why he didn't kiss her?

I see only two answers:
1: He loves her, but he didn't kiss her. Indeed, Mikasa wanted to kiss him before they die. It was impossible that they could survive, and before her death she wanted to say her love, and kiss him as a goodbye. That's why Eren didn't kiss her. Because that would have meant that he accepted to die here. Instead of that he stood up and faced the titan. He said that he would wrap the scarf around Mikasa again. That means that he would protect her, and also that they were not going to die now, so she didn't need to say him goodbye.
2: He doesn't love her romantically, so obviously he didn't kiss her. But what he says still have a very important meaning, of course.

To be honest... The case 1 is really beautiful to me but I can't proof that it's the truth. Of course, the contrary is also true.
I can't be categorical, I really don't know what is the truth here... It's hard to say what's going on in Eren's mind. What is sure is that he was definitely not rejecting her. (Plz stop say that 😞)

Don't misunderstand me. I'm sure that Eren has really strong feelings for Mikasa, I just can't technically proof that this is love. I want to be objective, so I won't say that he loves her but just that "I don't know". But of all the characters, Mikasa and Eren have the strongest and more beautiful relationship in my opinion. This scene between Eren and Mikasa doesn't prove or disprove Eren's love, but I'll tend to say that it's still an argument because of what Eren promised her.

In order to understand Eren's feelings and try to find out how they could have evolved, we must analyze Eren's personality and its evolution. Let's go.
At the beginning, Eren wants to be strong, he wants to kill all the titans. He wasn't rejecting Mikasa's protection because he doesn't like her or because he found her presence annoying, but because it makes him feel weak. And he really does not like that... If he wants to kill them all, he has to be strong. Moreover it seems that he can't see the feelings that Mikasa has for him. Or not in the right way, he might have thought she was just excessively grateful. I believe that he was really obsessed with his revenge, or maybe he was just very ignorant, acting like a kid. He must have thought that she was mothering him. In chapter 97, we see thanks to Reiner's flashback that Eren was almost crying because he was thinking that he was not strong enough to accomplish his dreams, despite all his efforts. The truth is that he has always been complexed like that, but he was hiding it with his anger...

However, Eren changed. The little angry boy became a man. It started about season 2, when he said he still can't do anything in episode 37. Step by step, he accepted his weakness and we start to see his true feelings.
He felt stupid for having thought that his titan power was his own strength. Moreover, there's is a special scene that marks his evolution: he beats himself up. At this moment he rejects the one he was before. He definitely wants to change, because he hates some parts of himself.
Unexpectedly, he lost his characteristic anger. This was replaced by an total inferiority complex for a few chapters (it was already present before, but it was not evident, unlike his anger, although here it becomes obvious). He was like "I'm so useless, I don't deserve to live, I've nothing special, I'm weak", etc... I admit that I didn't like when he was like that, it looked like he lost all his determination and strength... I personally don't think he's weak or useless but just... Normal. Obviously he is weak compared to the titans, or to the Ackerman. But I guess it was a necessary step towards his evolution. After that he looked grown up: He said that he could not become as strong as Mikasa or Levi (I don't know what about you but I find so sad that Eren tried to be as strong as them, and he didn't even know this was not possible... No wonder he feels weak if he compares himself to them). At this moment we knew that Eren stopped seeing Mikasa as someone he wants to surpass. That's extremely important because I figure that the main reason why he was mean to her was that he was complexed by her being so strong compared to him. It's in chapter 72:

And in several scenes after that, Eren accepts Mikasa's protection and her help, because now he doesn't care about being weak or not. He is just grateful for her attention, and he appreciates it.

For example in chapter 70: (The "Don't treat me like an old man" is ironical of course, otherwise he wouldn't have thanked her)

Or in Chapter 74 (sorry for the low quality, that's all I found). Note that this scene looks like the one where Eren gives her his scarf, but it's the opposite. It has a huge importance in my opinion):

And after the basement, although we don't see him that much, he seems to have a kind of constant sadness. (cf chapter 90)

This is what I personally think about the current state of Eren's character: He is still determined to become free, but he is no longer dominated by his own emotions. I think he has been affected by the memories he received and the events he had to go through... I think having seen all this pain and sadness changed him.

According to chapter 97, we know that he is mature and serious now. Just look at his behavior, his words... It's sure now. He has changed. He doesn't have a bit of hate or anger anymore. He is just intelligent, mature, serious, etc. It's as if all his bad sides disappeared to leave only the good ones. I found him changed after the basement arc, but now he's even more matured. I'm proud of Eren. I find the way he evolved throughout the events so inspiring. Now, look at him now and tell me if we can definitely affirm that he would be able to have love feelings and that he cares a lot about people. I'll answer for you: Yes we can. Honestly, Eren would be able make Mikasa so happy, he is such a nice person now...

So, he is not going to be mean with Mikasa, yelling at her or rejecting her protection or her presence at his side, because he finally grew up. No, it's the opposite, he'll take care of her and his friends and fight for them (and not for revenge).
Anyway, now we've said that , let's back to his relationship with her.
I've said that he does​ not see her as a sister.
I've said that he cares a lot about her.
I've said that he would protect her if he had to.
So, can I say that he loves her? Actually... no.

Well, I think this is where most of Eremika shippers are overinterpreting: all the arguments I gave are not enough to definitely proof that Eren loves Mikasa. I mean, I need more clues. Because, if he really does love her... It would be more obvious, wouldn't it? There would be more signs, like in the way he looks at her (the gazes are very important to determine a relationship) or in the way he talks to her. However, it's possible that he doesn't want to show his feelings, or he doesn't realize them yet.

So, why doesn't he accept Mikasa's feelings? Many possibilities:
Maybe he has not realized Mikasa's feelings (Yes even if they are obvious it's possible that he doesn't understand them in the right way).

Maybe he sees her as a childhood friend and he has not changed his mind yet.
Maybe he just doesn't love her... Once again, if this was true it doesn't mean that he will never love her.
Maybe he doesn't want to show his feelings for some reason. (Like not feeling ready or thinking that he doesn't deserve it...)
Maybe he focus on his fight for freedom for the moment and he's waiting for the end of the war.
(Personal theory:) Maybe he doesn't want to be loved because of Ymir's curse...
Maybe (and more probably) he needs more time to understand his own feelings. In Chapter 50, it was probably still too soon for Eren, he had not finished his evolution yet back then...

However, let's assume that Eren doesn't love romantically Mikasa yet... It still can happen. And that's what I personally think... I don't believe he was in love with her back then, but I think he will learn to love her romantically in four years. I said that Eren has grown up. Perhaps the next step for him is to accept Mikasa's feelings, and to finally show/realize/start developing his own feelings for her. It would be a logical suite for his evolution, that's the most important thing. Since his feelings evolved with his personality, we can wonder what are his feelings now he his so mature. What is interesting in Eren's character is his evolution, it wouldn't be logical if he already loved her before his change.

Maybe if they survive this war, Eren will have some place in his heart for some love instead of anger, hate, pain or sadness... The manga seems to follow this way. For example in chapter 97, we see that he is not angry anymore, even towards his enemies. But he still has a sad face. The fact is that we don't know his feelings enough for the moment to be categorical. Also, even if it's not obvious, all the events in the manga take place in a short time (except for the fall of Shiganshina's arc). And feelings need time to become clear... That's why I'm impatiently waiting for the next chapters: I want to know how his feelings evolved in these 4 years.

In next part I'll sum this up, conclude, and finally say in a nutshell why I ship Eremika.

This was my opinion about Eren's feelings for Mikasa. If you have any other arguments (against or for Eren's love), please give it in the comments, I would love to talk about it, and complete this part with it to make it as precise as possible 😉

Thanks to AckermaJeager for his precious help!

This is probably going to be edited, to add details, more arguments and the references, and maybe if there is a character's evolution revealed in a new manga chapter.