WARNING: This is Incredibly Sadistic.
She didn't know when it all began, really, and she'd spent a lot of time thinking about the subject lately. It could have started anywhere from the first time she laid eyes on her short figure and noted her presence or even the first time she'd heard her name, confident and commanding and utterly bored in voice. The only thing she could be sure of, though, was when she'd noticed it. Seeing her completely and utterly obliterate Eren in hand-to-hand combat (although it was more like feet-to-shin and flip) and sparking her ire, she'd noticed, for the first time, the intensity of her feelings for Annie Leonhart, and though she was only sure of the burning contempt in her mind at the time, she wasn't so sure now that was the only feeling she'd felt then.
She knew now that, beyond the urge to strangle the blonde, she also wanted to descend upon the smaller girl and trap her between her thighs while she did so, hands on the pale, delicate curve of the girl's throat, squeezing enough to hurt but not to kill. To feel Annie's heat pulse between her legs and against her very core, and then mark her all over with blood and bruises to make her ready for consumption. She wanted to devour her, every inch of her and every mark she made, licking and biting and fingering the wounds she'd created-
"Mikasa."
She blinked. Blinked again. Her brown eyes flashed as she took in the dark storage cellar she vaguely recalled being ordered to clean and then the object of her desires staring unblinkingly at her from the stairwell, almost as if she had seenthe exact images and vulgar scenes playing through her mind's eye and did not care one bit that she had been fantasizing those desires.
Outwardly, she did not react, master as she was with her mask. "Annie," she replied. Cold. Hot underneath.
"I was sent to help," the blonde uttered tonelessly, and took the last couple steps down onto the cold stone floor. Without a word, she crossed the dark cellar, illuminated by the light of the torch at the end of the stairwell, the only source of light there was in the place. Her eyes, Mikasa noted, were such a clear, sky blue that did not accurately reflect the depths of darkness which resided in both their hearts, and she reached out before she could stop herself and grasped the girl's neck to get a better look at those glowing orbs.
Annie did not move.
"I only want, need, help in one way," she told her, and added pressure to her grip, gazing deep into those eyes. She was rewarded with a flinch, slight, but Annie had shown her the weakness she was seeking. Yet the blonde did not challenge her authority.
"Take what you need."
She was almost disappointed at how easy it all was, but she did not need to be told twice.
Turning abruptly to the side, she slammed Annie's head against the stone wall and swept her palm across her cheek in a resounding slap, following the movement again with a backhand going the opposite direction. Her knee came up instinctively not a second later and rammed the girl's gut before sliding down and firmly placing pressure at the junction between the blonde's legs. She leant forward, breathing hotly on pale skin, and whispered in her ear, "You asked for it."
Then she tossed her to the ground by the neck and stepped on her torso, wondering briefly whose stomach would win the competition for most toned girl of the 104th class. Impatiently, she reached down, grabbed the thin fabric of the girl's shirt and ripped the fabric up and over her chest, forcing Annie's arms to go up as well and allow the shirt to be removed as quickly as possible. Not wasting a second, she flung the shirt into the darkness and planted a firm kick into the newly exposed flesh, sending the poor girl flying back into the wall.
"I win," she stated, observing Annie's quivering form.
"Is this about winning?" Annie wheezed. Mikasa stepped close and bent down to get a better view of Annie's toned stomach, idly ingraining the form into her brain. Toned, but not chiseled.
"No," Mikasa answered. "It's not." And punched her in the face. She held back, however. There was no need to knock out one of her teeth. No one wanted to see that. "Stand up," she commanded.
Annie slowly stood, leaning heavily back against the cold wall and shivering at the contact. Her body admitted defeat, but her spirit remained strong, her eyes defiantly meeting Mikasa's own and blazing with some emotion she couldn't quite place but recognized as one she currently shared. No, this wouldn't do. She cast her gaze around the storage room, looking, searching, seeing boxes and bottles and paper and rags, and reached for a fairly clean strip of cloth. Perfect.
Grasping her neck once more, she pulled Annie roughly forward and wrenched her jaw open, shoving the cloth in and wrapped it around her head, tying it closed at the back and gagging her. For the first time, Mikasa heard Annie utter a noise, a whimper, and a pleasurable shiver traveled down her spine at the sound. Almost. She breathed deeply, noted her pounding heart, and stepped back.
Annie was a mess of red and purple and blue, having been cut sometime along the way as a bleeding shallow gash on her forehead indicated, and she had a bruise forming around the eye Mikasa had punched and one large one swelling up along the right side of her belly from the kicks. But what excited Mikasa the most, however, was the anticipation she saw in Annie's blue eyes.
She threw Annie to the ground and straddled her. As an afterthought, she picked up Annie's discarded shirt and tied the girl's hands together despite knowing that Annie wouldn't dare retaliate or be more than a means to an end. Then she leaned down and bit the porcelain, naked junction between the girl's neck and shoulder, sucking and licking and eliciting a throaty moan from the blonde's muffled mouth, feeling the vibration through her lips. Heat waves traveled up and down throughout her body and settled at the increasing throbbing she felt between her legs, and she did not want to wait anymore.
Growling, she impatiently slid the blonde's chest bindings up until hardened pink nipples met frigid air, and dove down with her mouth to meet one, hand coming up to tend to the other. She wasted no time, only worked brutally and efficiently and was rewarded with moans upon muffled moans. Her unused hand slid down the side of Annie's torso, fingers trailing smooth skin, and then dug suddenly into the bruises she'd inflicted mere minutes before, evoking a cry of mixed pain and pleasure which reverberated wonderfully through her ears.
Separating with a smack, Mikasa panted hotly and sat up, wondering how much time she had left before their instructor came to check on them. They'd received harsh punishments for having nothing done, but she'd worry about that later. Now...
Her hands grasped at the zipper of Annie's pants, and she nearly ripped the material in her haste to open it. Then, without checking to see if Annie was mentally or physically prepared, jammed three of her fingers in and began to pump, neither fast nor slow, and listened to the shrieks of pain and the dirty wet noises from below and she increased her pace only until the cries of pain turned into moans of pleasure before slowing down her pace and then stopping altogether. She almost smirked at the buckling of the girl's hips when she did so, desperately needy as she was, and reveled in the absolute control resting in the literal palm of her hand.
Reaching up with her unused hand, she pulled the gag down and growled, "Beg."
And beg she did.
Just so we have some things straight so you don't feel this is somehow wrong, it is deeply implied in the manga and animation of Shingeki no Kyoujin that Annie is a masochist. (And obviously so that Mikasa is a Sadist). Many bdsm inclined people like this couple, and that's how many fan ifictions on them are written. Annie is not simply being tortured.
