Dean walked down the dark alley way, towards the impala, when he heard it; a loud crack like thunder and lightning. Dean looked up at the night sky but it was clear, the sound of muffled voices began to filter through the air as he kept on walking. He quickly pulled out his gun from behind his back, holding it up as he slowly turned the corner, braced to be met with some big bad but all he saw were Cas and Meg. They were talking faintly, and although Dean couldn't understand the words he got the tone, anger. He brought his gun down but didn't draw attention to himself, still trying to understand where the crack had come from, then it happened again. Meg shoved Cas' back into the brick wall, pressing her body up against his for a brief second, opened mouth ghosting over his. When she back away Cas, surprisingly to Dean, didn't do anything, simply lifted himself off the wall, which had a dent in the concrete, and walked forward to a smiling Meg, head cocked to the side with a hint of a smirk in the corner of his mouth. Dean stood back, about twenty yards, confusion flooding his face as he watched them interact, circling around each other as if in a duel, spitting insults he couldn't hear and drawing closer to one another. Meg stopped, a huge grin growing on her face as she swung at Cas, but he caught her arm, twisting it behind her, wrapping an arm around her waist to push her back against his own body, causing Meg to arch into Cas as his head dipped to rest on her shoulder. Dean suddenly realized the mood had changed when Cas began to slowly walk her back to the wall she had pushed him into earlier. Meg's face was forced into the wall and she let out a hiss as Cas' hands ran up and down her body, roughly grabbing at the jacket to tear off leaving only a thin dress hanging loosely on her frame. When Cas spun Meg around to face him he leaned in to kissed her, nipping at her lip first before crashing their mouths together. Dean stood still; eyes wide with horror and disgust as he watched angel and demon undress each other, Cas' trench coat and suit jacket being thrown to the floor, when a moan escaped Meg's lips it traveled all the way to where Dean was standing and right to his dick.
Cas slid his hands up Meg's thigh, disappearing underneath the dress to pull down her panties then push her legs apart, grabbing her ass to fit her legs around him. Meg moved with him, biting into his neck when Cas pressed his crotch to her, and worked his belt off, zipper down to wrap her hand around him. Cas groaned and bucked into Meg's grip, then pulled away to whisper something, something unkind, and Meg tilted her head back and laughed at him. Her hand wrapped around his wrinkled blue tie, yanking his mouth into hers, fingers slinking up from the tie to dig into his neck. Meg's other hand was still shoved in his pants, working Cas hard and her body shivered with obvious want when Cas dipped his head to kiss down her neck, stopping right above her breasts, teasing her. Meg clenched her legs around Cas' waist with impatience but that only cause him to slowly kiss back up her neck and when he lifted his head Cas had another small smirk tugging at his mouth. Meg shoved his pants down, not all the way, just enough and Cas thrust himself into her in one quick movement, causing her to let out another little moan. Cas began moving roughly, using all the force he could because he knew Meg could take it, and even if she couldn't he didn't really care.
Dean was still standing out in the open, staring at the pair, his breathing getting heavier and heavier and his erection growing. He couldn't pull his eyes away and when his pants became painfully tight he shifted and pressed the palm of his hand into the front of his jeans as if he could push his hard on away. His hand made contact at the wrong moment because Meg let out a loud gasp, her knuckles turning pale, gripped in Cas' hair, as he fucked her into the wall and Dean found himself jerking his hips against the pressure of his own hand. Dean shut his eyes for a moment trying as hard as he could to escape all the noise and the need growing inside him because this was Cas and Meg. He wasn't surprised about Meg, he just fucking hated her but he was shocked that Cas was going along with this. It's not like he cared, Cas could do whatever the hell he wanted but the thought of an angel and a demon having sex in public, up against a wall was odd in itself and oddly hot. The meat suit Meg had was attractive, no denying that, but the bitch that possessed it repulsed Dean and that's what he tried to tell himself, 'The body's hot, that's it'.
Cas and Meg were still going at it when Dean's eyes fluttered open, he was still aroused but he wasn't in need anymore. Cas groaned again as he tilted his head back, exposing his neck to Meg again and she took advantage of it, biting in as he pushed particularly deep, a small twitch when he felt that Meg had broken his skin. They gripped each other hard enough to bruise and Meg tried as hard as she could to pull Cas closer to her, to pull him into her more and Cas' thrusts became erratic as they both neared orgasm. Cas dug his fingers into Meg's hips, to pull him down on her fast and in time to his hips and Meg quickly pushed her hips forward into his and let out another high gasp when orgasm hit her. When Cas came his breath left his chest in a rush, hips still moving to milk his orgasm. Then it was over.
They didn't speak. Cas backed away and allowed Meg's feet to drop on the ground. She picked up the panties on the floor, not even bothering to put them back on, as well as her jacket which she slung over her arm. Cas was busy looping his belt back together when Meg started to walk off, not bother to say any sort of goodbye and frankly Cas didn't care, she did however wave her hand at him with a devilish grin as she walked. Thankfully she was going the opposite way that Dean was currently at, he still couldn't move his feet. Cas gathered up his suit jacket and trench coat, putting them on carefully and slowly, as if he hadn't just been fucking a demon, then vanished with a faint flutter a wings. Dean stood still for a good five minutes, recounting what the hell just happened, before he shook his head to rid himself of the images and found his legs apparently still worked. He walked quickly towards the impala and when he got in he jammed the key hard into the ignition, he wanted to get out of here as soon as he could.