Natural Twenty

Author's Note: Most of my works have a strong cherishing and romantic angle to them. This... Is not that. You've been warned.

The realism on this one has also been dialled way back.

Warning: This story contains scenes of non-consensual or reluctant sex.

---

If there was any simple way to summarise why Luc decided to go to university in a different city to his family, then it would revolve around four very simple words.

"Tell me to stop."

They were words that haunted him late at night. When he wanted his mind to shut down and let him sleep, it brought up those little words, and the tone that uttered them.

Memories of the little sister who relentlessly teased him with them, as she ever so slightly stepped over lines that should never be crossed between family.

It wasn't that he had a bad relationship with her.

For the most part, they were just brother and sister. They had their little fights, and then they went by. Both of them knew they could always call the other for help.

The problem was that... Every now and then, out of the blue, when he was alone around her she would do something crazy inappropriate. When he tried to stop her, she'd use those four little words, and... And he found it tempting not to stop her.

It had all started on her eighteenth birthday.

Or to be more precise, the morning after her eighteenth birthday. Luc had a little too much to drink during the party, and had expected to wake up hungover, and spend the day finding excuses not to climb out of bed.

What he hadn't expected was to be woken up before sunrise with Mia lying on top of his blanket, staring him in the face.

She'd seemed so excited, just like she had the night before. Luc hadn't suspected a thing. Just his grinning and cheeky little sister.

He'd groaned something about it being too early, which it actually was, and dragged the blanket over his head.

Mia laughed at him and yanked the blanket not just down but threw it off the bed altogether. "That's the point. You don't want to get caught like this."

"What?"

She'd shushed him, putting a finger to his lips, and then her other hand snaked around his morning wood, just his pyjamas between them. She didn't exactly start to jack him, just held him.

Luc swallowed nervously, "Mia..."

She'd smirked, and said those four words for the first time.

He had... Eventually.

His sister bounced to her feet, threw the blanket at him and laughed as she left the room.

That was the first incident, the first time that she'd cross the line and teased him. Making him wonder exactly what would happen if he didn't stop his beautiful sister.

Half the problem was that she was beautiful. Absolutely, utterly, stunning. If we were in another country, she might have been drafted into a cheerleading outfit.

Naturally wavy brown hair that cascaded down to her shoulders, bright blue eyes that were too easy to get lost in. Full lips, and breasts that other women would kill for.

She only got worse after that first moment.

Cornered a few times in the bathroom, including once where she didn't just grab a hold of Luc, but slipped her hand directly into his clothes before he even knew she was there.

Always whispering those four words.

Always making him want to stay silent, and see just how far she'd take it. To see if she was just fucking with his head, or that by some miracle the forbidden attraction really was mutual.

Luc regretted it each time, telling her to stop.

They never discussed it after she went out of her way to mess with him. Luc had tried, once or twice, and Mia had simply played dumb. As if she had no idea what he was talking about.

In the end... Getting away from her and the random surprise attacks seemed for the best.

All the same, he didn't cut off all contact from Mia. She was still his sister, and apart from those terrifying words, he got along with her well.

Which meant that soon after starting uni in another town, he found himself on a train headed back to her city, her home. It had been Mia's suggestion, and had entirely played into another aspect of who she was.

Game night, just the two of them.

---

"Welcome, to the game room!" Mia announced proudly, throwing open the door to the room she had been preparing ever since she had moved into her own place.

Luc entered it carefully, looking around suspiciously for the inevitable trap.

It actually just seemed like a normal nerd cave.

Mia's dice hoarding was as out of control as usual, taking up several of her shelves. Accompanied by all the usual cages, towers and rolling trays for them.

There was a loop of leather hanging down from the ceiling that seemed out of place at first, until he saw the rest of the virtual reality gear sitting on a shelf to the side.

The table in the corner of the room had inbuilt card holders and settings for placing models. Perfect for tabletop games, like the kind Mia always made him play.

She sprang onto him from behind arms going around his waist as she whispered in his ear, "So... What do you think?"

"You've been productive." Luc acknowledged, "Nerd."

Mia kissed his neck gently and idly fiddled with his belt, "That all you think?"

There it was.

The trap that was always waiting for him any time the two of them ended up alone. Making Luc fight with himself, knowing on one hand that it was incredibly wrong, and on the other that Mia was probably the most attractive girl that he knew.

He tried to knock her hand casually away from his belt, but she firmed her grip, expecting it. Whispering the words he hated to hear, the words that tortured him late at night. "Tell me to stop."

He didn't know how far she'd take it.

He knew that he did want her to cross the line, to keep going. He wanted to experience everything that she kept offering him. Hanging out that temptation.

"You're my sister. You aren't supposed to do things like this."

She nibbled his ear and slid the clasp on his belt open. Practically purring in his ear, "Then tell me to stop."

"S-stop."

Mia walked passed him, spinning around, "So... What are we going to play, tonight? I've got a new one shot that'll waste a couple hours that'd be fun. Pirate themed. Use my brand new table."

She always did that, too.

The moment he did tell her, it was done. Mia never mentioned again, never teased him. She went from total slut to perfectly behaved, and he wouldn't know when the next attack would come. Sometimes months would pass between Mia doing anything. Making Luc feel like it had all just been a bad dream. And then... Then she did something like this.

He wished he could turn the tables on her. Hear her struggle to tell him to stop, but she was his sister. He wasn't willing to cross that particular line.

Which was probably why she felt safe to do what she did to him.

He sat down as Mia quickly divvied up some cards, and grabbed a handful of dice from her collection, and a tower for him because he always complained that the dice hated him.

"Take a look. That's your character." Mia waved at his cards as she began setting up a model ship on the centre of the board.

Luc picked up his cards, and looked up at her in disbelief, "Are you kidding me?"

"Huh?"

"A slave. I'm starting off as a slave on a pirate ship." Luc said with irritation. "You starting on the bottom of the barrel, too?"

She flipped over her cards, "Um... No. Apparently not."

"That's so not fair." He said as he saw that she was the pirate captain. He already hated it when she played with him, with no intention of giving him anything. He didn't want to roleplay it as well.

"Swap 'em." Mia shrugged, nonplussed.

Luc took her cards, and was busy trying to guess the symbols and get a feel for the game when the thought crossed his mind. It really was innocent, just a tiny hint of payback.

If he played the captain, and she was a slave, he could order her around. See how she liked being toyed with. It was just a game, after all. He would just be leaning into it.

"Okay, so we'll just launch straight in, and I'll help you pick it up as we go along." Mia said sitting down. She pointed to one of the figures, "This is obviously you. Biggest hat, biggest pirate. You've just found that the chart for the target ship's route has been stolen by one of the crew. You suspect everybody. What do you do?"

Luc looked at the ship, "So... That's the first mate, probably. And these down here are the slaves? Which one is you?"

"Mmm... That one's the cutest." Mia chose her figure.

"As captain, I call all the normal pirates up on deck, order anchor dropped, and... Order them to crack out the wine or beer or whatever." Luc said.

Mia gave a small laugh, "Okay... You can do that. Aren't you worried more stuff is going to go missing, though?"

"Nope." Luc grinned, "Because I'll be the only one not drinking. Just pretending. Pirates are notorious for bragging. I'll just keep the party going. Speaking of, we need some people for serving."

She rolled her eyes, "The slaves?"

"Well, if you're the cutest we definitely need to use you. I order the first mate to choose the five prettiest."

Mia moved a few up on deck, "So, whilst the party is getting started, you notice that the door to your cabin has been opened a crack."

"Are you trying to railroad me into some storyline?"

She rolled her eyes, "I'm not that bad a Game's Master."

"You're always controlling. And I expect you'd love it if I actually called you a master." Luc laughed.

Mia made an exasperated sigh, "Actually, for your information, I much prefer to call the guy the master and be taken advantage of. But, back to the game, your cabin door has opened a crack. Roll an intelligence check. Bet you wish you could do that in real life."

The dice tower flipped upside down, and out they tumbled. Luc smiled up at her triumphantly, "Nat twenty. And really? The way you tease me? As if you're a sub."

"Not just board games in this room, you know. I wear the cuffs." Mia gestured vaguely to one of the top shelves. "So... You notice that it's one of the servants trying to sneak out."

"Slaves?"

"Yes, slave." She glared, and then moved the character, "In actual fact, it's me. The prettiest of the bunch. What are you going to do, captain?"

"Shouldn't you be calling me, master?" Luc said, trying to see just how far he could push his sister. Expecting she'd get exasperated and tell him to shut up. But, she started it.

Mia rolled her eyes, "Why? So you can cream your pants? I don't call anyone who can't make me cum, master. And you'd never be able to do that. Too gentle."

"How would you even know?" Luc laughed at her.

She crossed her arms, "Like I've never talked with your girlfriends before. Kaley was always more than willing to shoot the shit about how annoying you are. Said she counted you asking for permission one night, and got to two dozen."

"Kaley would have loved to be punished for that." Luc chuckled, "And she was. You ever think that maybe the reason all the girls complained to you is I might have a thing for brats? And they were trying to get overheard?"

Mia paused, looking at the gaming table carefully, and then up at him, "I don't believe you. Prove it."

"Prove what?"

She laughed, "I'm the biggest brat you know, Luc. And that's my thing. Ooh, here's a deal. If you can make me cum, oh gentlest of man souls, I'll do whatever you want. Whenever you want."

"Oh, stop it. You always do this." He said in annoyance, "Let's just play."

Mia shook her head, "I... I'm not just teasing. I haven't had anyone for a while. And you need a bit of trust for that kind of thing. You're hot, and I trust you. What do you say? Willing to make a bet to get your personal cum dumpster?"

"What. The. Fuck."

She rolled her eyes, "Told you. I'm offering a dom's dream, here. And you're not even biting."

"Oh, you'll get bitten, if you keep being a slut." Luc's patience snapped.

Mia smiled lopsidedly, "That a promise, is it? Call me a slut, again."

He stood up and walked over to the shelf, grabbing down the handcuffs, before he grabbed her wrist and forcefully walked her underneath the leather loop hanging down from the ceiling for the VR setup. Then, he put the cuffs through it and looked at Mia pointedly. "Put them on."

She glared at him, "You can't be serious."

"Now. Slut."

Mia's face twitched, and then went from annoyed to meek. She lifted her arms high above her head, and Luc heard the cuffs clicking shut around her wrists.

Mia's voice was nervous, "Don't lose the key."

"It's around here somewhere." He replied casually, looking her up and down, and beginning to walk in circles around her. Checking out his sister, tying herself up just because he told her to.

She stamped a foot, "This isn't funny, you said that -"

She cut off with a groan as he gave her ass a quick slap. He gave it another couple for good measure, watching her jerk happily with each one. "I think I'm going to enjoy this. Don't know about you."

"You get nothing, if I don't cum." Mia said firmly.

"Eventually." He replied, and reached around her to pat her pussy through her shorts. Grinning and using her words, "You could always tell me to stop."

"I-I can't." Mia swallowed.

Luc kissed at her neck, "No? You've been teasing me for years. Tell me to stop."

"I... I want..." Mia fretted and then stamped her foot, "Fuck you! Fuck you, Luc! What the fuck did you do to me?"

He shrugged and undid her shorts, sliding them down and off her waist. "You were always like this. You just didn't realise. I haven't done anything."

"No. I changed my mind. I'm not a slut!" Mia said, her voice cracking.

"Then tell me to stop."

Her head hung, and the cuffs moved noisily as she hung from them, "Fuck. I... I want to... I do."

"Then say it." He ran a hand up and down her pussy through her panties, feeling how drenched they were. "Tell me to stop."

"N... No."

He took his hand away, and Mia moaned, "No! That's not... You win. I wasn't... I can't stop you."

"You could say it." Luc hooked a finger around the edge of her panties, dragging them down slowly. Pausing at about knee height as he took in the sight of her reddened ass. "One word. Four little letters."

"Fuck's sake!" Mia groaned, "Just do it. Please. You want me to beg? I'm begging. Make me cum, Luc. Make your slutty little sister cum. She'll do anything for you. Just make her cum."

He dropped her underwear, stood up and roughly grabbed her hair, tilting her head back to look at him, "Anything?"

"Anything." Mia trembled, "I... I'm your slave, captain. Master. I'll do what... What you want."

"You'll come when I call you, slut?"

She gave a small nod.

Luc spanked her ass, "Tell me."

"I'll come when you call. I'll be your slut." Mia said, a hint of fear in her voice about her far he was going to take this.

Luc rewarded her, gently rubbing the outside of her pussy, feeling just how wet she was. But not to let her forget who was in charge, he reached up under her top, hand pushing under her bra and tweaked one of her nipples just a little.

"Hey!" Mia flinched.

He kissed at her neck and slipped his finger into the sopping warmth of her cunt. She let out a combined whimper and moan, "Oh. Oh, fuck."

Luc smiled at her response, "That's it. Now, slut, tell me. Was it all just a game? Were you just teasing me?"

"Y-yes." Mia said meekly, "I-I was just teasing you. I liked how it made me feel. Liked the way you looked at me... Like I was the sexiest thing alive."

He tweaked her nipple again, "Planning on fucking me, now, then?"

She glared, "Do I have a choice?"

He curled his finger inside of her playfully, making her gasp again. "You could tell me to stop."

Her face dropped, and she went meek, "I... I can't."

"Because you want it?"

She nodded silently.

"Tell me you want it, slut." He ordered.

She moaned weakly, "I-I want it. Goddamn you. Make me cum. Please... Fuck's sake. Make me cum for you."

"Then, cum, slut." He commanded her, as he suddenly began to violently fingerfuck her. He watched her carefully, the way her body jerked in the partially suspended position. Listening to her moans, hearing them as she approached her orgasm.

"Ooh, y-yes. Just like that! Just..." Mia groaned.

He listened, all so he could jerk to a stop. Right before she could finish.

He pulled his slick hand out and walked over to the table, and leaned up against it. He looked her up and down as she stomped a foot angrily, "You bastard! You fucking asshole! I was so close!"

"You said you'd be my slave. Do what I wanted."

Mia's cheek twitched and she looked down, "I-I did."

"All good things come to those that wait." Luc said and smiled at her frustrated glare. "Well... I suppose what I really want... Is to fuck you. Can't let you have all the fun."

She swallowed nervously, "Y-you really meant it, didn't you? That you're going to fuck me?"

"Yeah." He began undoing his belt, "I think I might just do that. What do you think? You going to cum on your brother's cock when he tells you to?"

"I-I..."

"You could tell me to stop."

She shook her head silently, "Y-you can fuck me. Fuck me any way you like. I-I'm your slut."

"Good. I intend to." He said and pulled off his pants, dumping the handcuff key with them.

He walked behind her, hearing her suck in her breath in anticipation, and instead he gave her ass a good slap. She whimpered, this time. Maybe he had hit her too hard.

It wasn't all about gratifying himself. He wanted her to be his slut, but he didn't want her to feel the need to run away from him. He was giving her an out, each time. "Slut... Next time I do it too hard, you have to say the word. Tell me."

Mia shook her head, "I... You can do what you want with me."

He grabbed her chin from behind, jerking her head, "I don't want to damage what's mine. Got it? So, don't let me."

"Y-yes."

"Good." He let her go, and tapped his cock on her slick opening a few times, "Tell me."

She spread her feet a little wider, and hung her head between her arms.

"I said tell me, slut."

"F-fuck me. Fuck your slut." Mia whispered.

He paused, and then lifted his arm and pushed his dick gently at her asshole instead. She gasped in surprised and jerked forward, but didn't say anything.

So he grabbed her hips, and pushed a little bit firmer, not enough to even start going inside, but enough to spell out his intent.

"N-no. S-ssss..." She trailed off.

He paused, "Slut?"

"S-stop." She swallowed nervously, as if expecting a reprisal.

He let go of her hips, "Don't want me to fuck your ass? I thought I could fuck you any way I wanted."

"Y-you can. Just... Not without lube. I... I've never had my ass fucked before." Mia trembled, "I'm still your good little slut. Y-you can fuck it. J-just... Th-there's lube in my bedroom."

He laughed and kissed her neck, "Good girl. You told me to stop. We'll see about that asshole later. For now, I'm going to fuck your pussy. Make you cum on me. That was my part of the deal, right? I have to make you cum."

She didn't say anything.

He grabbed her hips and shoved his cock inside her gaping warmth, all the way in. She managed a sound that was mostly moan but ended in pained grunt.

"N-not..." She stammered, and he felt her legs shaking, "G-give me a chance. Please."

He shrugged and stopped moving, "I'm not going anywhere. You like having your brother's cock inside you, slut?"

"Yes." She swallowed, and then glared at him, "Asshole."

"That comes later. Pussy for now." He retorted.

Mia rolled her eyes, making him spank her ass again. She gasped, and then thrust back on his shaft in response. He felt every inch of her enveloping him. He was filling her.

He stood still, waiting.