AN: Again mostly smut. Yes it is supposed to be like a bad porno that was my goal. Also this is my first smut fic so there's that too. Finally had time to finish this (been working on it for like a year) because of the ridiculous quarantine. Anyway, enjoy!

It was the first day of senior year and Spencer was finally home. His mom had come out into the kitchen to greet him home.

"So, how was it?" She had a summer dress on and her makeup made her face strangely colorful. Strange as in she never put makeup on.

"By it, do you mean prison?" he muttered. Before she could give him the classic pity look, he added, "Why are you all fancy today?"

"Oh, Daniel's taking me out tonight," she beamed.

"Ah, good ol' Dan the man. Have fun, don't party too hard." She scoffed at the very idea of "partying too hard."

Spencer escaped to his room before Dan could greet him and sulked for a while. He was assigned homework the very first day and was rather put off by it. He did it obviously, but was still grumbling about it when he shuffled into the kitchen again to look for a snack. Dan was there in his khakis and button-up shirt. He was the perfect suburban dad; he just wasn't Spencer's dad. Spencer's dad left him and his mom when Spencer was around ten. But it didn't bother Spencer anymore. It was his loss.

"Oh, hey, Spencer. How was school?"

"Peachy," he prompted sarcastically. But Dan wasn't annoyed, he just smiled.

"You're almost there, Champ." Spencer wanted to barf. Champ.

"Spencer, we're going to be back late, did you want money for food?" his mother asked him softly.

"N-no, I'm good. I'll find something," he assured hastily. He hated taking money from his mother.

"Well, okay. Be safe and don't stay up too late. I love you."

"Love you too, Mom." And with a nod from Dan they both left for their date night.

Spencer felt his whole-body sigh with relief. He was home alone. He hadn't been home alone since he was in middle school. He let a big, stupid grin stay on his face as he grabbed some snacks, wrapped himself in a big duvet, and headed into the living room instead of his bedroom. The flat screen TV was his for the night.

The next two hours were the most peace he'd gotten in a long time. It ended all too soon when the familiar slam of the front door vibrated through the house. He prayed silently that whoever it was had just forgotten something in the kitchen and was about to leave again. He was never that lucky.

He paused his show and waited, knowing the routine by heart. A bag dropped, the cupboards raided, fridge slammed, and the shuffling of those awful crocks across the hallway. She was home.

She stopped at the entrance of the living room and stared at Spencer for about a minute before asking through a mouth full of food, "What are you doing here?"

"I live here," he retorted. She swallowed the food finally.

"Well, duh, I just didn't expect to see you out of your cave, but I guess hermits can move after all." She moved closer to his position on the couch. "But you didn't leave your shell I see," she commented as she poked her index finger into the duvet until it found Spencer's arm. He wanted to slap her hand away but thought better of it. He didn't want to seem childish, especially not to her. She pulled back and left for her room down the hall without another word.

Spencer un-paused his show, grumbling to himself. The nerve that girl had to call him a hermit. It wasn't like he was obsessed with his phone or wore headphones 24/7. It was actually nice that she'd just pretend he wasn't there. He preferred that. He didn't want the prettiest girl in his grade to acknowledge him at all. She'd probably talk smack about him to everyone. Actually, she already does.

He stopped listening to his show with all these thoughts going through his mind and decided to just turn it off. Just as he did, an obnoxious base boomed throughout the house. And where was the source? Jennifer Jareau's room of course.

Spencer went into the kitchen again and put away the rest of the snacks. The music seemed even louder in there somehow, and the thought of the tiles falling off the walls drifted through his mind. And he knew that she'd somehow blame it on him.

With a mission created in his mind, he swiftly went to her room, even dropping the duvet on the couch on the way.

He was about to knock but noticed the door was a good foot open. He peered through silently, but it didn't matter over the music. And there she was, dancing in her full-person mirror. But it wasn't dancing per se. It was too slow, too sensual. All the while looking at herself, she slowly pulled off her jean jacket and tossed it to the side. She flipped her bright blonde hair and bit her lip as she dragged her hands down her torso. Then she smiled that annoyingly cocky smile.

"Damn, I'd fuck me," she gloated to herself and smacked her ass in the mirror. The jiggle was visible through the skirt and down her thigh. Then the shirt was gone suddenly and there was only the small, strapless bra.

Spencer unconsciously took a step into the room but slipped on an article of clothing left on the ground and fell face first into the door. The door creaked open and he met the ground. He saw the twirl of skirt and knew he was a goner. But at least she turned off the music.

"WHAT THE HELL WERE YOU DOING?" he never heard her voice go so high.

"I was going to tell you to turn the music down." He picked himself up and she was right in front of him now, bare as she was.

"It didn't occur to you to knock?!"

"Well, your door was wide open."

"THAT'S NOT AN EXCUSE, YOU PERVERT!" He couldn't help but stare when she stomped her foot and everything was right in front of him. But she grabbed a pillow anyway and starting swinging.

"Honest to God, JJ," Spencer said while blocking her blows, "I won't say anything about this again, okay?" One particular hit had him falling again, but this time he landed on her bed. She just wouldn't quit. She even climbed on top of him, straddling his waist to get a better hit at his head. But he got stronger over the time they known each other and he grabbed her wrists and pulled her down so they were face to face. "Stop. It." He accentuated through grit teeth. And she did.

JJ looked down at their position with a bewildered expression. "Are you hard right now?" Spencer's eyes widened.

"Wh-what?!" he spluttered.

"Well, I thought it was just your jeans at first but you're like, really warm so-"

"No! I'm not hard!" She grew silent then, her blue eyes boring into his hazel.

She hummed, "Interesting." Then she started moving, grinding herself against him. His eyes went wide, shocked into being completely motionless. Then he snapped out of it.

"What the hell are you doing?!," his voice threatened to crack.

"I wanna know what it feels like when you're hard," she said as if it was obvious.

"Why?" he hushed, eyebrows drawn together. She merely shrugged. "Y-you're my sister!" She rolled her eyes.

"Step-sister, Genius."

"But wh-what if your dad came in here and-," his grip loosened enough to where both her hands were on either side of his head, "saw us like this." His voice was a small whisper at their proximity.

A smirk danced across her lips, "Good thing he isn't home."

Spencer might have gotten away with telling her he didn't have a boner before, but there wasn't a chance in hell for that lie now. Especially with his face heating up as it was. She realized it too. She gasped, a mock-surprised look across her face.

"You like this, don't you? Being home alone with me, watching me change, being pinned down...," she sat up straight then, perching her butt on top of his everything. "I really am a tease, aren't I?" she giggled. She started moving again, with more determination this time. It was starting to hurt more than anything.

"JJ...," he whispered, making her lean down again. "You're not doing anything," he said flatly. She stopped moving.

"What?" she sassed, annoyed at his monotone interruption. "What do you mean I'm not 'doing' anything?"

"I mean all you're doing is pressing the jeans into my skin which isn't getting you closer to my consent." JJ stared dumbly for a moment, then her face blazed a hot pink.

"Well—it isn't like you'd know anything about this type of stuff. I've been all the way to third base," she said proudly.

"Good job, Princess," he muttered under his breath, but then a thought occurred to him. "Wait, only to third base?"

"I...," she didn't expect him to catch that, but he did. He was the genius of the school after all. "Yeah, I'm a virgin, but I'm not a prude, I swear. I wanna do it. But... every guy just sees me as a piece of ass, y'know? And, I wanna do it with someone that I won't regret doing."

"Then what the hell are you doing on top of me?" he couldn't stop his voice from getting deeper. She was still a virgin; what a miracle. His hands somehow got to her thighs, slowly inching under the skirt and towards her hips. He felt the smooth fabric of her thong and his mind went completely blank.

JJ looked into hooded eyes, full of lust. He was already panting with his mouth lazily open.

"This," she answered softly and kissed him. It was gentle at first, lips sliding slowly. Then a sort of desperation poured from it and it was messy and wet and they had to pull back to breathe. Spencer's hands had moved again, but this time around JJ, hugging her closely as if afraid to let her leave. JJ smiled.

"What?" the boy wonder mumbled distractedly.

"You're so cute," she swooned and kissed his cheek with an audible, "mwah."

"Y-you're the cute one," he murmured and swallowed past the lump in his throat. He felt like his skin was on fire.

"Aw, really?" she asked sweetly as his hands guided across her skin, making contact with the bra strap.

"Yes," his voice was clearer now. He expertly undid the strap, letting it fall onto his chest. "You are."

She was completely exposed now, the sleeves of Spencer's shirt grazing her soft flesh. A short kind of squeak left Spencer's throat without his permission. JJ laughed.

"C'mon, Spence, I can't be the only girl you've seen like this," she prompted honestly while slipping her hands under his shirt.

The goose flesh travelled all the way up his neck. Before he could stutter out his reply, JJ had already pulled his shirt over his head. She discarded it, along with her bra, to somewhere on the floor. With a gleam in her bright blue eyes and the making of a smirk across her lips, she unbuttoned his jeans.

"JJ," Spencer called softly. He grabbed her wrists, gently this time. "Are you sure?" JJ blinked at the question.

"Um. Yeah. You?"

"Yeah," his voice rasped out.

"Good. Now shut up and let me suck you off." Spencer's eyes went wide at first, and then he gave her a shy smile. She pulled down both his pants and boxers in one swoop.

"Hm. Not bad," she commented offhandedly.

"Thanks?"

"You're welcome," she smiled sweetly then slipped down to the floor on her knees. She grabbed him by the base and stroked him hard and slow, her blue eyes watching him intently. He stared back, not really sure if this was happening. Her hand felt so soft and small compared to his own. The neon pink nail polish on her perfectly manicured fingers made the experience even more surreal. Although definitely not unpleasant.

JJ examined the warm rod in her hand, weighing her options carefully. It wasn't her first time doing this but she always felt shy when she did it. She brought the tip to her mouth and licked from the underside to the slit, savoring the saltiness she found there. Spencer swallowed audibly. She looked up, making direct eye contact before looking away.

"Shut up."

"I didn't – "

"You didn't have to." She sighed, steeling herself. Then she wrapped her small, pink lips around him.

It wasn't a remarkable feeling. In fact, if he wasn't watching as close as he was, he probably wouldn't have felt much of anything besides a warmth incasing the head of his member. But the way she looked, how gently she started bobbing up and down, the way her blond hair kept slipping past her grasp... He ached in a way he never realized he could.

Spencer sat up a little bit and started gathering her hair together. He even took her scrunchie and tied it in a ponytail. JJ was surprised enough to pull back and look at him curiously.

"You are so beautiful," Spencer gave a small smile in return, caressing her check with his thumb.

"Spence –," before she could finish her thought, he crouched down and stole her lips with his. It was soft and passionate and very... wrong. "Spence," she tried again. His lips moved from hers, trailing down her neck, her shoulder, her chest. She gasped as his mouth enclosed over a pink nub, licking tenderly. Holding onto his biceps to keep from trembling, she tried again but only a guttural moan escaped her throat.

This was just sex, right? Just a one-time thing to let off some steam. It's not like they could date or anything. That'd be sick. JJ just hoped her step-bro was on the same page.

Spencer wasn't on any page or even thinking coherently. He was acting on impulse, instincts. She was beautiful and willing and, at the moment, his. He should have been scared. Hell, a part of him was scared, but the damn hormones nearly blinded him enough for him to throw all of his concerns out the window. It wasn't until that moan reached his ears that something inside him snapped.

He bent down, scooped the little blonde in his arms, and pulled her right into his lap again, her warmth on top of his. The only thing that separated them was her thin, cotton thong. He nearly popped the clips on her skirt and threw it like it was on fire. Her newly exposed hips and thighs felt like silk under his long fingers.

He slipped two fingers around the waistband of her thong and let it snap back against her pale skin. JJ giggled, noticing his open-mouthed breathing and the flush traveling down his chest. At that moment she knew she had complete control over him.

"C'mon, Spence. Take them off. I know you want to," she challenged sweetly. Suddenly she was pinned on her own bed, looking up into the eyes of what she thought was a nerdy little dweeb not an hour ago. His eyes were a wonderful shade of chocolate, warm and endearing and hungry. So, maybe she shouldn't have teased him that much. Too late now.

Spencer leaned down and started nibbling and pecking her neck, making JJ whine softly. Her hands traveled across his pale torso and came to rest against his shoulder blades. She lightly dragged her painted nails down his back and he shivered. He pulled back and saw her little smirk. He couldn't help but smile.

"You think you're so funny," he husked out.

"Oh, I do. I really do." He grunted in return and finally slipped off her thong. With both of them now bare and her blue eyes looking up expectantly, he hesitated. "What's the matter, dork? Finally short-circuiting?" And that was the push he needed.

"Y'know," he glared icily, grabbing the underside of her thighs and pushing them up towards her chest. "You are easily the bitchiest girl in the entire school." He slid his hand down her inner thigh and slipped his middle finger inside her. Her smug aura dropped at the new sensation and she bit her lip. "But you are the hottest. I'll give you that." He added his index, stroking her slowly and barely stretching her. "Do you play with yourself, JJ?"

"Y-you're such a perv," she mumbled as a blush crept up her cheeks. He chuckled darkly.

"Perhaps. Do you ever think about me? When you touch yourself, I mean." He waited for her answer, still stroking her slowly and brushing her clit every so often. She managed to scoff.

"As if," she lied. He took a deep breath and removed his fingers.

"Well," he quipped while hovering over her, his lips centimeters from hers. "Guess I'll have to fix that," he whispered hotly. His member was barely touching her lips before he pushed the tip inside.

JJ gasped, mostly at his boldness. She realized that at some point she started holding her own legs apart. She looked down while he eased himself further into her until he was fully sheathed. The most she could feel was the pressure.

"Hm," she hummed thoughtfully.

"What?" he asked, now somewhat anxious.

"Oh, nothing..." She reached a hand up and gently brushed his hair back, looking at him curiously. Yet again, she was able to amaze him. "Are you, uh... gonna move anytime soon?" His admiration quickly dissipated into annoyance.

He pulled out halfway and slammed into her again, expecting her annoyed "that hurt." Instead he received another light gasp and a pleading look. Then he understood.

Spencer sat a bit straighter, angled himself better, and did it again with more purpose. This time she moved herself closer to him, preparing herself to receive him. Before he knew it he was moving in and out of her, both teens adjusting themselves and encouraging the other. Spencer tried to capture the moment in his mind: her mess of blonde hair on the bed, her hooded blue eyes, her cute nose, her plump red lips, the flush across her usual perfect and tan skin, and the way her entire body reacted to him.

"Hnnnn, Spence... -err," she panted. She felt the pressure and heat build and build. God, Spencer actually was really hot. She couldn't believe she hadn't thought of this before. A perfect cliché of an underdog nerd getting the most popular girl. His own step-sister. JJ snaked her hand down to her clit and rubbed herself frantically.

Spencer himself was on the brink and decided, responsible man that he was, to pull out and finish. He matched JJ's speed and soon came with a groan.

JJ felt her nerves explode and the sparks traveled through her legs and up her body. After a satisfied groan, she collapsed on the bed. Both teens, sweaty and spent, thought about just laying there together for a moment, until Spencer turned toward the door.

"Did you hear that?" he asked quietly. JJ rolled her eyes.

"Paranoid much? They won't be back for a while." He glared at her, then picked up all his clothes and headed out the door. "Where are you going?" she called after him.

"What's it to you?" he called back before JJ heard the bathroom door shut. She rushed out of her room and pounded her fist on the door.

"I was literally about to shower!"

"Well, that sucks for you," he taunted. She tried the doorknob. Locked. "Were you seriously about to break into the bathroom when I'm naked?"

"I'M NAKED, TOO, DUMBASS," she all but growled. "I'll get you for this Spencer Reid."

"Sure, you will, Jennifer." And that was the moment JJ decided her little step-brother would rue the day he was born.

AN: Hi, me again, just so you know I just started season five on Netflix so if y'all could refrain from any spoilers that'd be greatly appreciated.

But if you have any requests, I will eagerly await your reviews or pms. I love this ship very much and may continue writing one-shots for them.