Disclaimer: I don't own Shingeki No Kyojin, nor the image. They belong to Isayama Hajime.

Author's Note: So sorry for not publishing earlier! I was too busy and I couldn't finish this one-shot on time. However, here it is at last. Expect the next one later today. Also, I want to thank everyone who has been reading this story, has put it in their favorites or is following it. Especial thanks to mshadow18 and theluckyshot who took the time to review it. Thank you!


Title: Doki Doki

Prompt: Heartbeat.

Summary: Suddenly,her heart started beating hard against her chest, and her cheeks turned a pretty shade of pink. What was that feeling, anyway? Why did she feel funny things inside her belly? All Mikasa knew was that she had never felt this way before. Mikasa-centric.

Mikasa's relationship with Eren had always been hard to define. True, she had been adopted by the Jeagers, so technically she was Eren's sister, but she had never really felt as his sister. They had spent a great amount of time together, playing and talking with Armin about the outside world, and though that would have made them friends, for Mikasa Eren Jeager was more than that.

She was filled with feelings of gratefulness towards the boy, the boy who had saved her, the one person who gave her a reason to keep on living; she was forever indebted with him for giving her a home. Eren simply was precious for Mikasa in a way few could understand. Mikasa soon gave up at the idea of naming her relationship with Eren, after all, he was by her side and that was all that mattered to her. However, soon those feelings started changing.

It all started just before they enrolled in the military. It was an uneventful peaceful evening, during one of the few days in which Eren wasn't filled with rage and thoughts of vengeance. He, Armin and Mikasa were resting under the shade of a tree, talking about the things they wanted to do in the future, imagining how it would feel to finally see the ocean for the first time. They stayed that way for what seemed like hours, until it was time for them to have dinner. They started walking, but Eren stopped walking, looking curiously at Mikasa.

"Mikasa, wait." He said, gently holding her wrist. His face came close to hers, and his fingers got tangled in her hair. Suddenly,her heart started beating hard against her chest, and her cheeks turned a pretty shade of pink.

"There, you had a couple of leaves in your hair." Eren said, giving her one of his heart-melting smiles. The feeling returned once again, making her shiver lightly. What was that feeling, anyway? Why did she feel funny things inside her belly? All Mikasa knew was that she had never felt this way before.

Ever since then, things started changing inside of her. Every time Eren's hand accidentally brushed hers, that same feeling would return. Whenever Eren smiled at her, she felt as if her heart would burst from the happiness of seeing him giving her even a tiny smile. And then came the longing; the longing of actually holding his hand, of embracing him, of laying her head against his shoulder, and, even more embarrassing, of feeling his lips against hers.

However, even then, she couldn't name the feeling. Mikasa knew it was probably something her mother must have felt for her father at some point, but she wasn't sure it was love, whatever that was in the first place. It wasn't until one fateful night at the girl's dorm when she finally got some answers.

"And when he smiles at me, I feel butterflies in my belly. Every time we kiss, my heart starts beating so fast I fear I may die!" Hannah told them one day, when Krista and Mina asked her about her feelings for Franz. It was sort of a secret, she said, but she trusted all the girls enough to tell them every little detail.

"Oh Hannah, you're so in love with him!" Krista exclaimed, rejoicing at the thought of people finding love even in a world like theirs.

"Yeah, I do love him, and whenever he…" Hannah continued talking, though Mikasa stopped paying attention to her.

Love. Realization dawned upon her. So this was what she felt for Eren. She was hopelessly in love with Eren, there was no denying it. Mikasa blushed at the thought, and her heart started beating faster. Doki, doki. But now the question was what was she going to do with her newfound feelings? Clearly she couldn't be as straightforward as Hannah was about them ─for that she kind of envied the girl─, perhaps the solution was to hide them until the proper moment, since there were more important matters to think about, like actually getting into the military, for example. However, she had to wonder for how much time she would be able to hide them from Eren, and everyone else…