Summary: When Natsu has a question about sex, he goes to the person he trusts more than anyone, his English teacher, Miss Heartfilia. She decides the best way for him to learn is with a hands on lesson, literally. Modern AU. Role playing.

*To be clear, Natsu and Lucy are in an established relationship. This is just them acting out one of their combined fantasies.*

Pairing: Natsu/Lucy (Nalu)

Rated M for foul language, sexual content, and adult situations.

Prompt: Role Play (Nalu love fest 2017)

Genre: Romance, Humor

Word count: 4.2K


Safe Sex

The sound of the door creaking open caught Lucy's attention. She looked up from her desk, smiling when she saw Natsu poking his head past the door. "Miss Heartfilia?" he started, already getting her blood pumping faster. "Can I ask you something?"

"Of course," she said, keeping her voice as calm and professional as she could. She stood, gesturing for Natsu to take a seat at the lone desk in the center of the room.

Natsu stepped in, easily taking her breath away. He was wearing his old Magnolia High shirt, the material snug on his muscular body. He had been smaller when they were both in high school, but she still appreciated the way he looked back then, just like she admired how he had grown since those years.

Natsu took his seat, a soft blush on his cheeks when Lucy stood up, showing him her outfit. Her long sleeved white shirt was a bit too thin and tight on her, easily letting him see the outline of her black lace bra. Her pencil skirt hugged her hips, showing off her womanly curves. Natsu's eyes dipped down, stopped when he saw the stockings. It was a weakness of his, and Lucy was clearly playing on that.

"So," she started, moving until she stood in front of her desk. She leaned back, resting her ass on the edge. "What can I help you with today?" While she spoke, she fiddled with the top button of her blouse, 'accidentally' unbuttoning one in the process. Her chest strained against her top, something Natsu was very aware of. "Do you need help on your senior paper?"

Natsu shook his head, managing to look flustered as he said, "Some of the guys were talking about... about sex, and I didn't understand some of the things they said. I was wonderin' if you could help me?"

Lucy cocked her head, giving him a concerned look. "Didn't you take sex ed like everyone else?"

Once again, he shook his head. "I was absent that day." He sighed, leaning back in his chair. Lucy was impressed, he actually looked exasperated. "I missed this stupid class, and now everything's confusing!"

Lucy tapped on her chin before sliding the tip of her finger to her bottom lip. She dragged it along the pink flesh, smiling when Natsu's sharp eyes followed her movements. "I suppose I can try to help, but I'll need some supplies first."

She walked to the desk, making sure to sway her hips as she made her way to the first drawer. Opening it, she pulled out a single condom. "I confiscated this from a kid last period. I'm sure he won't mind if I use it."

Natsu gulped, the blush on his face darkening. "Wh-what are you gonna do with it?" He looked nervous, but his tone was full of anticipation.

Lucy offered a warm smile as she went to sit on the front of her desk. She made sure to cross her legs slowly, letting Natsu catch the shortest glimpse of her matching black panties. "I'm going to show you how to properly put it on. Now, we'll just use a banana to—"

She cut herself off, pretending to look upset. "Oh shoot, I don't have a banana with me. Hmmm." She looked around the room, but she knew she wouldn't find anything to use around her, purposely putting away anything that might be considered penis-shaped.

Lucy's brown eyes lit up when she looked at Natsu again. "I know! We can use you as an example." She saw the way Natsu furrowed his brows, but she didn't give him a chance to speak before instructing him to stand up.

When he was directly in front of her, Lucy sank down to her knees, hearing Natsu's soft gasp when she put her hands on the waistband of his gym shorts. "Hold still like a good student, Mr. Dragneel. I'm going to take these off."

Lucy waited a few seconds, giving him time to tell her to stop if he wasn't comfortable with it. When he said nothing, she pulled his shorts and boxers down, revealing his thick, half-hard cock. She allowed him to step out of his clothes before tossing them aside, knowing they wouldn't be needed for the duration of their scene.

Soft hands slid up his thighs until they brushed over his short pink curls. One of Lucy's hands grasped his cock, lightly stroking him to encourage blood flow. Natsu sucked in a sharp breath, his confused tone sounding convincing as he asked, "But Miss Heartfilia, isn't this against school rules?"

Lucy shook her head, admiring the throbbing cock in her hands. He grew quickly, the apex of her thighs pulsing as she imagined him slamming it inside her. "No, this is for school." Her voice was as soft as her hands, gently caressing his cock and balls. "It's a demonstration. It's fine. You just enjoy it."

Natsu threw his head back as he moaned, a bead of pre-cum leaking from the tip of his cock. "Yes, teacher."

He enjoyed the way she stroked him, using a technique that was a little too slow, but it kept his blood roaring in his veins. Just as he was about to ask if she could speed up, he felt his cock being consumed by a wet heat.

Green eyes snapped open as he looked down, seeing Lucy's mouth around his cock. "Wh-what are you doing?" he asked, trying to sound confused, but he didn't know if he was acting well enough. He wanted to keep the fantasy going, hoping his enthusiasm didn't ruin the scene.

Lucy slowly pulled back, her lips making a popping sound when she withdrew his cock from her mouth. "I'm uh..." she started, fumbling with a good excuse, "I'm making sure you're properly lubricated so the condom goes on easier."

She licked along his shaft, keeping her eyes on him as she lapped around the tip. "We wouldn't want you getting injured during this demonstration, would we?"

Natsu nodded, his voice coming out as a groan. "N-no, we wouldn't."

Lucy gave him a few lazy strokes, smiling when his hips bucked, wanting more friction. "Shall I continue?"

He couldn't nod fast enough. "Yes, please."

Her lips wrapped around his cock again, her hands wandering over his lower stomach and upper thighs as she sucked him. She kept his gaze as she took more of him into her mouth, making sure to run her tongue along the underside so he received as much pleasure as possible.

When she started gripping his ass, Natsu moaned, "Lucy."

She stopped, pulling off his cock to stare at him. "Mr. Dragneel, it's highly inappropriate for you to call me by my first name." She had to fight the urge to smile, finding the irony too sweet considering she was sucking her 'student's' cock. Still, she played her role like a champ. "Do you want detention?"

A cocky grin crept over Natsu's features, making heat pool in her lower stomach. She absolutely loved his smiles. "Maybe you should spank me?"

Lucy shook her head, finding it harder not to smile. She had to bite her inner cheek to keep her lips from twitching. "There's no corporal punishment here." She leaned in, lightly flicking her tongue over his head. "Now, do you want me to stop and explain why this school doesn't do corporal punishment anymore, or would you like me to keep going?"

"Keep going," he replied, no hesitation in his voice.

She grasped his cock with her hand, giving him a pump before guiding him back to her open mouth. Saliva trickled down the corners of her lips when she took him in deep, nearly getting his tip in her throat before she was pulling back. Natsu whined at the lack of contact, but she ignored him.

"Okay, I think you're ready." She lifted up the foil package, letting him see it. "You need to check for any holes in the condom. You can do this by pressing on it from both sides with your fingers. If it deflates, there's a hole."

She let Natsu check the condom wrapper before telling him to also check the expiration date. "Yeah, it's good."

Lucy nodded as she accepted it back, ripping it open to pull out the condom. "Pay attention. I'm only going to show you this once."

Lucy rolled the condom over his cock nice and slow, making sure to stroke him as she went while keeping her other hand busy by pinching the end. "How does that feel?"

"Really good," he moaned, staring down at her with hazy eyes.

She smiled. "Perfect. Safe sex is very important. You don't want to go around catching a disease or something. You have your whole life ahead of you."

When the condom was fully on, she stood up, placing a hand on his shoulder. "How does that feel?"

"A little weird, but not bad."

"Understandable," Lucy whispered, giving his cock a few pumps. "Just making sure it stays on."

Natsu swallowed thickly, his blush traveling down his neck and over his chest. "S-sounds good, Miss Heartfilia."

While still holding his thick erection, Lucy said, "Now, after the condom is on, it's usually safe to have sex. You still need to get your partner's consent, of course."

Natsu furrowed his brows, voice thick with need and cock twitching in her hand. "I still don't get it."

"Get what?"

"Sex," he said as if it were obvious. "How's it supposed to feel that good. I mean, I know it feels pretty good in my hand, but how's a pussy any better?"

Lucy shivered at his crude choice of words, her thighs rubbing together to soothe her dull pulsing. "Hmm, how do I explain it?" She managed to look halfway convincing, but she knew Natsu could see through her act.

Natsu, being the helpful guy he was, asked, "Maybe I could get another demonstration?" He had the gall to sound cheeky about it, but Lucy couldn't blame him. She already knew he was getting that 'demonstration' before he asked.

Still, she pretended to think about it, tilting her head left and right. "Hmm... I supposed I can show you a video of two adults having sex." She already knew that was riling Natsu up. She loved teasing him if she could get away with it.

Natsu pressed on, taking a step closer to her. Her hand slid along his cock, his breathing heavier than normal. "I'm more of a hands on learner, Miss Heartfilia."

Lucy wished she wasn't wearing a damn pencil skirt, wanting to press a hand between her legs to dull the ache brought on by his fierce gaze. He looked hungry, ready to devour her, and she absolutely loved it.

Lucy slowly nodded, her hand squeezing his cock once to draw out a groan. "You certainly are," she breathed before clearing her throat. "Okay then, with your permission I will teach you."

Natsu nodded, his voice just as airy as hers. "Yes, please."

"Okay, well first of all, what are you interested in? Females? Males? Or perhaps both?"

Natsu swallowed, his eyes tracing her curves before letting his gaze linger on her exposed cleavage for a moment. "Female."

Lucy took a step back, finally letting go of his cock so she could unbutton her shirt. "Very well then."

While she stripped her shirt off, Natsu found himself asking, "Why?"

She gave him a coy smile, already knowing he was going to regret his earlier answer. "Because, if you said male, I would have demonstrated with my ass."

Natsu's lips parted as his jaw dropped, looking just as torn as she thought he would. "Is it too late to change my mind?"

She snickered to herself, shaking her head. "For this demonstration, yes. Now, when dealing with a vagina, there are a few things you'll need to do before you can have sex."

She unzipped her skirt, shrugging the material off her body. Clad in only her underwear, stockings, and heels, Lucy moved to sit on the desk. She felt Natsu's eyes wandering over her body, giving her the confidence to keep going. "You need to make sure she's properly wet, either with her natural arousal, lubricant, or a combination of the two."

Lucy crossed her legs, hiding the wet spot on her panties. "You'll have to make sure she's prepared first." She beckoned for Natsu to come closer, seizing his cock as soon as he was within her reach. She gave him a few pumps before letting go, smiling at his confused expression. "It's to make sure you stay hard."

Natsu mumbled under his breath, but she easily heard him since there was little space between them. "That's not gonna be a problem." His words were combined with another glance at her body, his fingers twitching by his sides.

Lucy's heart pounded as she continued, knowing if she didn't maintain control she was likely to beg him to just fuck her. It was what her body certainly wanted, but the scene they played out was too tempting to pass up on. Kicking off her shoes, Lucy scooted back on her desk, shamelessly spreading her legs.

Natsu's eyes fell to her panties, his cock jumping involuntarily at the sight. "Fuck," he murmured, transfixed for a second by the thin piece of fabric covering her womanhood. If it weren't for Lucy talking, he would have zoned out.

"You'll have to finger the vagina to make sure it's prepped. To do that—"

"Can we stop calling it a vagina?" Natsu asked, cutting her off. "It sounds weird."

Lucy nearly panted as she opened her mouth, already knowing the answer to her question before she asked. "What would you like to call it?"

Her heart thrummed when he said the word, his eyes glinting with something dark. "Pussy, preferably."

Lucy nodded, her blush consuming more of her body. "Okay, pussy it is." Her blood burned hotter as he kept staring at her, looking ready to take her across the desk at a moment's notice.

"So, why do I need to prep it?" Natsu asked, not bothering to wipe the smirk off his face.

Lucy took a deep breath, loving the way this man affected her. "So it doesn't hurt the woman."

"I thought it was gonna hurt no matter what since it's her first time? Isn't the hymen thingy blocking it?"

Lucy shook her head. "The hymen isn't covering the entrance to the va— pussy, completely. It's a thin piece of membrane that needs to be stretched and loosened. It's never supposed to break or tear."

"How do you stretch it?" Natsu asked, voice turning rough.

"Y-you can do that with tampons or exercise, but the thing that really helps is regular masturbation or fingering."

Natsu set his hand on her inner thigh, holding her body down. "So, it doesn't have to hurt the woman her first time?"

Lucy could barely shake her head, her mind almost blanking as she met his gaze. "It shouldn't hurt, at all. M-maybe some discomfort if the cock is..." Her eyes trailed down his body until they landed on his erection. "... above average, but it shouldn't cause pain."

Natsu nodded, hand sliding closer to her panties. He only stopped moving when she asked her next question. "Are your fingers clean and nails clipped? That's very important as well."

He nodded, remembering taking care of that right before he knocked on the door to her 'classroom'. "Yeah."

"Okay," Lucy sighed, body yearning for his touch. "You may begin."

"You're going to have to tell me what you like," Natsu teased, letting his fingers brush against her covered slit. "I'm new to this."

Lucy wanted to call him a damn liar. He knew her body better than she did, but she didn't dare break character. "Take off my panties."

Natsu didn't hesitate to hook his fingers over the waistband, pulling the damp underwear down. He tossed them aside before forcing her legs open again, loving the whimper that slipped past her lips. "Sorry, teacher. I think I like things rough."

"That's okay," she whispered, throat dry as she waited for him to touch her again. "Here, give me your hand. I'll show you want feels good."

Natsu allowed her to maneuver his hand, pushing one finger into her dripping pussy. Since she wasn't a virgin and already soaked, she told him to try two fingers.

"You're so wet," he mumbled as he felt along her inner walls. His skin was burning and his cock throbbed painfully, but he kept fingering her, wanting to 'learn' all she had to teach him.

Lucy nodded, trying to sound professional. "That's because I'm aroused. When a woman is—"

"Why are you aroused?" he asked, lips pulling back to reveal his sharp teeth. She shuddered, his teasing tone doing wonderful things to her body.

"Because that feels good," she whispered, moaning when he added a third finger, stretching her. "Mmmmmm!"

Natsu chuckled as he lowered himself. "Glad you think so." That was all he said before lapping over her clit, making Lucy gasp.

"Wh-what are you doing? That's not part of it," she scolded, but her body leaned into his touch, desperately wanting his hot tongue on her.

"I thought I was supposed to get you prepped?" He continued thrusting his fingers into her, drawing out a string of curses as he ravished her body. "Do you not like this, Miss Heartfilia?"

Natsu's devilish tongue licked her again, causing Lucy to whimper as she squirmed on her desk. Before she could answer, Natsu said, "I can stop if you really want me too?"

"No," she gasped, not wanting him to stop his ministrations. Her body craved any touch he supplied her with. "That won't be necessary. You can keep going."

Natsu grinned before sucking on her clit, his fingers continuing their assault on her pussy until she was gushing with her natural juices. Just as Lucy was near her edge, Natsu withdrew his fingers, licking each digit while keeping her gaze.

"Can I fuck you now, Miss Heartfilia?"

"Yes!" Lucy found herself begging, needing him inside her. She felt far too empty. "Please!"

Natsu grabbed the base of his cock, lining it up with her dripping core. He slowly eased himself in, pushing past her wet folds to spread her inner walls. "Oh wow," he mumbled, fingers digging into her thighs. "You're so wet, it's just slipping in!"

He hunched over, his brows furrowed as he pushed further in, enraptured by the pleasure overwhelming him. No matter how many times he had been inside of Lucy, he would never get over how incredibly amazing she felt wrapped around him.

Lucy moaned, her back arching as her eyes slid shut. "And there's no pain, feels nothing but good!"

Natsu waited until he was fully sheathed inside Lucy before leaning in, delicately cupping her cheek. His eyes were pleading with her before he even opened his mouth, his voice coated with lust and need. "Can I kiss you, please?"

When she didn't answer right away, Natsu started pulling out until just the head of his cock rested inside her wet heat. He gave no warning before thrusting into her roughly, making her gasp.

"Yes," she moaned when he pumped into her body again, this time slower. "F-for the purpose of this ahhhh! D-demonstration, yes."

Natsu didn't hesitate to lean in the rest of the way, capturing her lips as he rocked into her. He felt her legs wrap around him, her heels digging into his firm backside. He continued to fuck her, not bothering to act like he didn't know what he was doing. He was pretty much done with their little role playing, just wanting to feel Lucy all around him.

However, something devious sparked within him when he felt Lucy's pussy tightening around him, her thighs shaking as her hips jerked. He ended the kiss, deciding to plant his lips against her collarbone as he asked, "What's happening?"

Lucy flushed a darker shade of red, her heart threatening to beat through her chest. Natsu knew exactly what was happening, but she gave him what he wanted to hear anyway. "I-I'm c-coming!"

Natsu growled at the feeling of her convulsing around him, her pussy trying to milk him for all he was worth, but he wasn't finished with her yet. "Damn! You feel so fucking good!" He gave her a few rough thrusts, loving the sound of their skin slapping and her juices sloshing. "So fucking amazing!"

Lucy let out a prolonged moan when he slowed down, fucking her more gently than she wanted, knowing he was trying to make himself last longer. She purposely squeezed him while whimpering, urging him to fuck her faster.

Natsu obeyed the silent command, hips snapping to draw a choked sob from her. He wanted to go for a while longer, but his release hit him so suddenly, he had no way of stopping himself from spilling into the condom as he growled against her chest. He gave Lucy's body a few short thrusts before stopping, thoroughly exhausted.

"So much better than my hand," Natsu muttered, voice ragged and heart pounding.

He slowly pulled out, feeling sweat clinging to his skin. He heard Lucy clear her throat before she tried sounding professional. "N-now you'll remove the condom," Lucy started, her eyes glazed over as she blinked away her lust, "and dispose of it in a trashcan."

He rolled the condom off, making sure his cum didn't spill out of it before he headed towards the corner of Lucy's 'classroom'. He was just about to throw it away when Lucy said, "Wait!"

Natsu jolted, wondering what he did wrong. He watched as she stumbled off her desk, legs wobbling as she grasped a tissue. She failed to hide the way her legs shook when she walked to him. "Wrap it up. We can't risk anyone seeing it."

Natsu looked around, confused for a moment because they were in their house. 'Who would see it?' He parted his lips when he remembered they were still in character, Lucy playing the concerned teacher who didn't want to get caught.

Being a cheeky guy, Natsu smiled. "Nope, we wouldn't want that." After throwing away the used condom, Natsu sauntered towards his 'teacher', placing his hands on her waist. "Do you want me to help you get off again?"

Lucy shook her head, a lazy smile sliding onto her lips. "I'm very satisfied." She straightened herself up, gently swatting Natsu's hands off her. She pulled her shirt and skirt back on, tucking a few loose strands of blonde hair behind her ear. "Now, clean yourself up. I'm going to assign you some homework to make sure you understood what I taught you."

Natsu grinned, his curiosity piquing. "Oh yeah? What kinda homework?" He thought she might tell him to masturbate, but what she said was much better.

"You should try this again with someone you trust to get the hang of it. You're..." she let her eyes fall down to his spent cock, then back up to his eyes, "a very gifted student, but there's always room to improve."

"I don't have anyone I trust more than you, Miss Heartfilia. Can't I just practice more with you?"

Lucy almost wanted to slap that silly grin off his face, but she couldn't. He looked too cute. "Maybe. I guess a few more lessons couldn't hurt, as long as you don't tell anyone what happened here today. It'll be our little secret."

Natsu chuckled, crossing his arms over his chest. "But I thought you said it was okay, since it was a demonstration? Why can't I tell anyone?" Natsu smiled like a fool, wanting to see how Lucy dug herself out of that one. She looked adorable, even if Natsu hated that particular word.

However, he couldn't deny that it fit her perfectly in that moment.

"It is, b-but some people might not understand. It's just better this way." She cleared her throat, realizing just what to say to ensure her 'student's' silence. "Besides, if people found out, I'm sure other students would come ask me for help with their sex questions."

She saw the way Natsu's eyes narrowed, clearly not liking the idea of anyone else touching his woman. She smiled sweetly at him before setting a hand on his chest, feeling his rapid heartbeat. She leaned in, brushing her cheek against his before whispering into his ear. "We don't want that, do we?"

Natsu barely held back a growl as his hands gripped her waist, pulling her closer to him. "No, definitely not."

Lucy nodded as she pulled back, feeling Natsu's grip loosen before letting her go. She patted over the scar on his cheek, loving that his flush was still present, even if it was fading. "Good." She walked backwards until she was pressed against her desk again, using a hand to shoo him away. "Run along. I'll see you tomorrow for class."

Natsu found himself laughing as he grabbed his discarded clothes, not bothering to get dressed before slipping out of Lucy's study. He felt a little silly walking naked through the hall towards their bathroom to wash up, but he didn't care. 'Man, I love that woman.'

Natsu would hold onto her until the end of time, knowing Lucy was the best treasure anyone could ever wish for. He loved every bit of her, including their adventurous sex life.


The end.

Remember to tell me what you thought of this one-shot! Did anyone catch the Easter egg in this story? "She looked adorable, even if Natsu hated that particular word." Which one of my versions of Natsu hates that word? I'll give you another hint. It's my main high school au. :P Please leave a review and tell me your thoughts. :D

*Just in case anyone was wondering, in this fantasy, Natsu was pretending to be a senior (18 years old). In the story they're both in their 20's and have been together for many years. Also, don't fuck your teachers. I assume if you're mature enough to read a smut fic you would be mature enough not to pursue any type of inappropriate relationship with a teacher, but in case you didn't know, don't do it. I understand stories can have an effect on real people, but readers also need to take some personal responsibility.