A/N: I decided to contribute to the Mikasa/Eren side of the fandom. Please let me know if there are any mistakes!
"No one gives a fuck about you want," is what Eren tells her.
His head collides with hers, and the pain momentarily causes her eyes to water as she listens to him. Eren is furious – his eyes are burning with purpose, anger, and a thrill that terrifies her. She knows that he has been waiting for this; for the chance to finally kill titans but all Mikasa can feel is her own fear, swelling inside of her – close to bursting. Eren is too headstrong and stubborn, if she isn't there he will die – she knows it, she knows because for all of his determination and foolhardy anger he has always needed her to save him in the end. Always.
She reaches for his arm, tugging at the fabric of his jacket, the leather is rough against her finger tips. Mikasa breathes deeply, swallowing and holding back the tears that burn in her eyes.
"Please, don't die," she whispers, her heart beating wildly. This is all that she can do to hold back the panic, but she needs to trust in his abilities so she doesn't fight it when he glares at her and snatches his arm from her grasp. When he walks away from her, she feels as though she is losing him. Ever since the death of his mother, Eren has pushed himself further and further into his training, and further away from her.
She has always been there to center him when he is too emotional and too reckless. Mikasa took his mother's words to her very seriously because she has seen with her own eyes how often his rage and ambition has either gotten him nearly either injured or killed. She is grateful to him – because that same rage has saved her life, but she knows that it will one day be his undoing if she isn't there to protect him
But as Mikasa watches as he walks toward the battle field, eyes hardened and determined she knows that there is nothing that she can say to stop him. She can't save him from himself and she wonders if she is finally losing him to his own anger.
When she learns of Eren's death, she realizes that he was absolutely correct – nothing in this world gave a fuck about what she wanted. The thought was strangely calming and it confirms what she had always known to be true.
After all, the world is merciless. Why should she have expected anything different?
Eren was alive.
Mikasa didn't care how – she wasn't going to ask how he had become a titan, or why. She clings to him tightly and listens to his heartbeat; it is slow and steady, but it is there and that's all that matters. He smells of smoke, and his skin is burning, but she holds him tightly even as the skin on her hands beings to welt. Eren has never been more beautiful, he has never been fiercer or more fragile than he is now – in her arms.
She promises herself that she will never let go of him again, no matter what it took. She would protect her family even if she had to save him from himself. She swears it.
After the trial, Eren is confined to a small room in the scouting legion's hold. Mikasa joins the legion soon after because she knows now that if she is not with him he will die. She can't depend on others to keep him safe – she can't even depend on Eren himself. He is tidal wave of emotion and irrationality and being a member of the legion means being under the constant threat of death.
Titan or not, Eren is not invincible. She will kill anyone and anything that tries to harm him because he is all that she has left.
Anxiety nearly consumes her and every time that she closes her eyes and attempts to sleep she imagines Eren in his titan form being consumed by the other titans. He had come so close to death that day and the thought only makes her more restless. Mikasa shifts and turns in her cot.
It's still hard for her to imagine that Eren is actually alive – that he has someone come back from the cusp of death, returning just as wild and unruly as he'd always been. Now that she has tasted what it feels like to lose him, Mikasa can't imagine going through it again. Part of her wonders if this is a dream, and if she is really dead. If the titan who saved her was actually an illusion and her life has already ended crushed between the teeth of a giant.
When she was a child and still suffering from nightmares after her parents' death, she would sometimes quietly sneak into Eren's bedroom. She would crawl into his bed and curl up beside him. It was so strange; even then he was the only thing that could make her feel safe. Eren would never complain when he woke up to find her there – he'd never even mention it in the morning, but she woke up with his arms around her. She hadn't sought him out in that way since his mother's death but she finds that can't stop herself from going to him now.
Mikasa decides that she won't stay long. She just needs to see him there – see him sleeping. She needs to see him alive.
Quietly, Mikasa stands outside of the door to his room before steeling her resolve and opening the door. She's not very surprised to see that he is still awake, lying on his bed with his eyes wide open. Relief floods her, and she moves to leave just as quickly as she had come but he glances at her before sitting up.
"You know, you're not supposed to be here," Eren says, but his voice lacks its usual bite. Mikasa pauses, before deciding to close the door. She will stay. This time – he needs her.
"I know," she responds, "I just don't care," and she walks to the bed and sits down. She can feel his eyes on her and he wordlessly moves over to make more room for her. The cot is a small one, meant for one person but they manage to fit, even though she finds herself pressed against him. Being this close to him flusters her – they aren't children anymore, are they? – but she bites her lip and hardens her face into an unreadable expression.
"Can't sleep?" Eren asks softly, his back is turned from her. She wishes that she could see his expression. She wants to know what he's thinking, and she wants to help him. Mikasa has never been one to push for an answer from him when he is so guarded, so she simply says, "No. But it seems as though I am not the only one."
He chuckles, but it's a forced sound. "Maybe," he says before he stops speaking entirely.
There are many things that Mikasa wants to tell him – she wants him to know that she will be with no matter what he was. He could be a titan and she would never abandon him. Even if he lost himself, she would be there to bring him back. She wants him to know that he is her family, and she is his. She has always been his. Instead, she finds that she can't bring herself to say any of that. Her own fear of changing their relationship or him misunderstanding her as he so often does is crushing.
She lies still before letting her forehead rest against his back. He's still so warm, as though heat from his titan form is still radiating off of him. Had his temperature always ran this hot? Eren's back tenses at her touch before relaxing.
She doesn't remember falling asleep, but when she wakes up she finds Eren's arms around her, tight and secure. He must have turned over in his sleep. Mikasa sighs and wraps her arms around him, clinging to him as though he were her lifeline.
Mikasa doesn't know what will happen in the future, and the uncertainty of it makes her not want to think of it. But, she thinks that as long as she is with him then she can do anything.
I won't let you go again.