She tasted tears when she kissed Armin's cheek, as Eren embraced them both. They were sky laced with earth, shells filled with dirt and blood and the transparency of clouds, and their bodies mixed like falling rain. Three moving as one could not be done, but they were one moving as three, as they had always been. With clothes off and shut into privacy, there were no barriers separating their hearts.
Mikasa was strong, and liked to lead, to guide, and observe. Her dry lips were pressed all over Armin's face, until they had removed his grief, and she turned to the other boy who was holding her waist, kissing his lips to consume and convey all the love overflowing.
Armin was hesitant, and liked to be touched, his body greedily absorbing whatever pleasure was bestowed onto it, be it Eren's bites or Mikasa's kisses, their strong hands, occasional clawing or hot, needy panting into his ear. He lay at the bottom as he watched the people who made him whole kiss over his body, and raked their muscular bodies without envy.
Eren was strong, and he was hesitant, unsure of what he was doing, thus moving without thought. He liked to let go, and he liked to own, to worship and be worshiped, to kiss and be kissed. He tasted the salty tears of Armin's on Mikasa's tongue, and then he tasted the hot skin of her neck, leaving marks which would be hidden when they were no longer alone, marks he knew she would stroke when no one was watching.
They were grounded with steady motions, with no distractions, with three hearts beating in sync, blood rushing through three different bodies which could have been one. They traded places without hassle, their bodies like eels, unable to knot and stop. Shyness was long overcome, and Armin taking Eren's sex into his mouth was no stranger than Mikasa's hands on his behind, spreading him open, tongue against his entrance. Eren's hand blended easily with the soft blonde hair, and his voice held the passion of a beautiful dusk sky, where colours blended so smoothly.
Ever changing, but always the same; the way a sun travelled the heavens; they shifted positions again. Eren's hand snuck between Mikasa's legs, Armin's mouth around her nipple, and she was down on her back, only with them. They used the skill her soft moans reminded them of, with quick fingers and a suckling sound. She pulled Armin off to kiss him, tasting the precome of Eren's in his mouth, and consuming it along his breath. She could have whatever she wanted of him, of both of them, now and forever.
Again came a switch, when she was close, and wanted to prolong the night. Standing on her knees, spread for Armin, she held his arms to keep him steady. His eyes were a clouded day, but the sun shone through when she granted him a smile of comfort.
On the other side of his body was Eren, passionate and eager, already moving his slicked fingers inside of Armin. When his sex replaced them, pushing his thickness into his second body, Armin gasped, loud and clear. But his body did not lift from the ground, for Mikasa was there, keeping him safe, keeping them both safe, in their serenity of loneliness mixed with company.
Armin leaned his head up, and lapped at her exposed sex when she least expected him to. Her eyes were on Eren, calculating his movements, tracking his pace, so she shuddered in surprise. Armin was good with his tongue, better then Eren and better than she was, when it came to talking, kissing, and pleasuring her down there. Her legs throbbed, and her breathing quickened.
Eren wrapped a hand around Armin's neglected sex, when he pushed inside of him again and again. His thrusts were too violent if he forgot to, but Mikasa was there to make sure there would be no blood, no anger and no failure this time. Seeing Armin moan against Mikasa's sex, with his face buried but bobbing Adam's apple well showing, Eren could only speed up. The body was tight as always around him, for it was meant to be taken like this, same as him, same as Mikasa, no matter in what way they chose to proceed.
Thunder erupted in the sky between them, the sky which separated a trinity to cruelly, as his grip started to slip. His thrusts were faster, harder, and he barely comprehended it, not until Mikasa's hands were on face, steadying him and making sure he did not fly off, before she kissed him fiercely, with all the lightening surging through their bodies.
United as three, they found pleasure, for it was how they were meant to be. Minds entwined, bodies entwined, three shells filled with shared memories, shared love, shared pain. After they were all done and spent, they lay against the earth, not bothered by filth or discomfort, for it was only transparency. Above them they saw the sky which they laced, reflected in their eyes.
The tears were dried off, and they had their shared solitude for a moment longer, in this moment of tranquility.