Yanno when someone writes you a prompt they expect you to like, and you sort of obsessively love it there and then? That was basically what happened with this one.

The same "accidental sex" prompt list (that inspired Vibes, and will go on to cause other fics) spawned this one.

"You made an inaccurate assumption about something and I'm going to teach you the truth" + "You don't what insert kink is and I can't explain without showing you" + "I showed you insert sexual thing as a joke but now you're turned on"...

basically Valka read 50 Shades Of Grey, and Hiccup... teaches her better. BDSM flavoured incest. Or incest flavoured BDSM. Whatever tickles your boat or floats your fancy.

(also fuck 50sog.)

-HTTYD-

She wasn't sure why she was reading it, honestly. It had been a gift from her friend, as a joke when Valka had drunkenly lamented being single a while since her divorce. It wasn't as though she hadn't had offers, requests for dates and so on, but nobody had really set her on fire or caught her attention. And after several years in a passion-less marriage before she and Stoick agreed they were better friends than lovers, Valka wanted someone who really created a spark for her.

The book... it was intriguing, she supposed. Offered views into things Valka had never experienced or even paid much thought to. And in a way, it certainly excited her to read. Valka put that down to a lack of outside stimuli, rather than a deep interest in these acts of depravity. It was supposed to be an erotic book, no? So it made sense that it was able to incite arousal somewhat, surely? And from what Valka had heard, the books were very popular. So she shouldn't feel guilty about sneaking in a chapter or two now and then, no?

Perhaps reading it at the kitchen table with a cup of tea and a couple of biscuits hadn't been her wisest idea. Because that was how her son caught her with it. And judging by the look on his face, Hiccup certainly knew what it was.

"You don't actually read that shit do you?"

In light of her reading material, Valka didn't think she could chide him for his language.

"It was a gift!"

"That crap isn't worth the paper it's written on."

Given his liberal, open upbringing, Valka was amazed Hiccup seemed so revolted by something as tame as his mother reading erotic fiction.

"I didn't know you were so prudish."

Rooting through the fridge for a drink, Hiccup's head appeared back from around the door.

"Quite the opposite. I'm offended by anybody who thinks that book contains good BDSM."

The book almost fell from Valka's hands in shock at his blunt answer, her son quite calmly drinking from the carton of smoothie. It was his, so he could do what he liked, she supposed.

"Is... is it not?"

Placing his carton back where he got it, Hiccup wiped his mouth before crossing the room and plucking the book from her hands, holding it as though it were dirty and repulsed him.

"This book has as much place in BDSM as I have in Worlds Strongest Man."

"And you know... about those sorts of things?"

She and her son had talked sex before - Valka wanted him to not be clueless about condoms and safe sex when he eventually got to that point - but she'd never expected to be asking Hiccup these sorts of questions.

"You could say that. And this" he tossed the book away, landing messily on the side "is not what it's about. He treats her like an object to be acquired, a transaction. Submission is a gift, a bond. If you can't trust your Dominant to at least respect your limits, you shouldn't be in a scene with them. When submission isn't offered, it isn't submission. It's abuse."

His voice took on a new timber as he spoke, eyes wistful, obviously picturing alongside his words.

"I see."

Was it warm in there?

"Sorry, it's kind of hard to explain BDSM to someone without" he gestured loosely "demonstration... I mean. I could show you."

"Hiccup!"

"What? Oh. Right. Another thing that book" he said the word with a degree of distaste "gets wrong... BDSM isn't all about sex. Sometimes it is just about trust. Or pain. Or freedom. An exploration into the darker side of yourself, within the confines of a scene that will end and you can leave it behind. It can be about testing your limits. Sure, it can be a way to get off, but that is not all there is to it."

His... calmness, his confidence. They surprised Valka. She'd always thought of her son as a little awkward. It wasn't a bad thing, he'd inherited it from her after all, but this smooth tone of his and lack of any nerves whatsoever? Strange on his familiar face.

"I don't know son."

Hiccup cocked his head, surveyed her coolly.

"What's wrong mom? Don't you trust me?"

"Of course I do!"

"Then what's the problem?"

Phrased that way, Valka almost agreed. Except, there was no way she could justify letting Hiccup do... hel, she didn't even know what? Surely?

Fingers brushed her shoulder, made her jump slightly as she looked up into Hiccup's eyes.

"Hey. I would never make you do anything you didn't want to. Consent is the cornerstone. But you can live in blissful ignorance if you want. Just promise not to learn from that bloody book."

Was she being ridiculous? Valka had certainly been intrigued by the book. And Hiccup said it didn't have to be about sex, which admittedly made her all the more curious. Another thought sprang to mind.

"How, exactly, do you know about this sort of thing?"

Hiccup ran a hand through his hair, sighed.

"Heather isn't my girlfriend. She's my submissive."

She blinked. A few times. Valka wasn't quite sure how to answer that.

"And that's a different thing?"

"Well, some people date their subs. Not always. It's more an agreement that I'm her Dom. She'd need my permission to see anybody else. It's complicated, but it's completely her choice."

"I see."

"So. You want a demonstration or not?"

"I hardly think it would be appropriate."

"Says who? Most people would say kink is inappropriate on the whole. Does that make it so?"

Valka tapped her fingers against the side of her cold teacup, contemplating her son.

"You seem awfully... eager to insist I let you show me."

Hiccup shrugged.

"I like newbies. There's something about teaching someone how to unlock themselves that I love. And I know how you felt stifled by domestic life for years. I can show you a way to feel free, rather than worry you will go off and find someone who does not have your best interests at heart."

That all sounded tempting, Valka was ashamed to admit.

"Ok."

Surprise flickered across his face - Hiccup hadn't expected her to agree, it seemed. But he didn't backtrack or recoil. Just straightened up, phone in hand.

"You're not dressed right. Change into something that can come off easily" at Valka's own shocked look, Hiccup chuckled "don't worry. It's just because clothes and restraints rarely mix well. If you ever feel uncomfortable, you can say stop, and I'll never ignore it. But given that I came out of you, I think shyness about your body is a little redundant."

Phrased like that, she felt silly. And a little strange. Skin tingling in anticipation, Valka stood and turned away.

"See, you're off to a good start already."

"Huh?"

"You did as you were told. Go on. Come to my room when you're ready."

He didn't say changed. He said ready. Valka suspected those two would be very seperate events. Seeming quite calm, Hiccup gestured for her to head upstairs first, then followed sedately, entering his bedroom far more calmly than Valka felt he had the right to be. She fussed far too long about what on earth he could have meant she should wear. Delaying. Buying time really.

Hiccup's bedroom door was ajar when she stepped out into the hallway again, heard him talking on the phone.

"Honestly, it's like you say these things intentionally to get yourself in trouble. Yes. I will call you later, so don't forget to keep your phone with you. Good girl."

His voice was like liquid silk on the phone, talking to Heather - who he had initially introduced to his mother as a girlfriend, though that appeared to simply be a cover for the truth of their relationship, which apparently solely included this world of depravity. Gods, what was she doing?

"Are you sure about this?"

Finding her feet had already carried her in, Valka nodded at her son, who himself had changed into slimmer fitting clothes - a simple black t-shirt and jeans, but they hugged his lean shape, tapered waist and broadened shoulders.

"As sure as I can be."

Hiccup didn't look... perverse or leering, merely calm and intrigued. Valka had half-expected to walk in and find a huge selection of questionable sex toys lying around, a sudden and harsh introduction to deviancy. Instead, Hiccup approached her slowly, holding only some fabric in his hand.

"Before anything else, you need to pick a safe word. It means stop everything, end scene, no question. You can say stop, but for some people there are different levels of 'stop' and a safe word is absolute."

"What should I pick?"

Hiccup shrugged.

"It's your word. Something you'll remember. Something you aren't likely to say otherwise."

She pondered, still a little offset.

"Cloud."

Hiccup didn't laugh at her choosing something like the name of her cat. He just nodded.

"Cloud it is. If I do anything you don't like, then tell me. If anything is too much, tell me. Are we clear?"

He held her gaze, still in that cool, calm mode as he asked. Valka nodded.

"Say it."

There was an unmistakable note of command in his voice.

"Clear."

"Good. Is it alright if I blindfold you?"

"Do you need to?"

"No. But deprivation of one sense will heighten your others. And I get the feeling you will relax a lot faster if you aren't looking at my face the whole time."

Trying to steady her breathing, Valka nodded. Hiccup reached up placed the blindfold on, fiddling with it before asking softly if it was comfortable. His lowered voice seemed to brush against her ears like a faint but real caress, already demonstrating how taking her sight made her other senses heighten. Hiccup kept talking in that low, silken voice, peeling away her shirt with nimble fingers and explaining it to her as he went.

"This is bondage tape. It only sticks to itself, not you."

Even the feeling of her own hair brushing her bare back was causing goosebumps to erupt across her skin, Valka wrought tight with anticipation as Hiccup wrapped the tape around her wrists, almost too tight but he pinched and prodded her fingers, rubbed the back of her hands to check blood flow before moving on.

Already, she realised, Hiccup had her in an incredibly vulnerable position. She couldn't get out of the binds on her wrists behind her back, she couldn't see, and Hiccup had already removed one article of clothing. He could be doing anything and she'd not know. Completely at his mercy.

It was probably wrong how utterly thrilling she found that.

"If you start to get pins and needles or anything in your hands, let me know. The bonds aren't that tight, but you're a beginner and I don't want you overestimating your body."

She nodded. Hiccup's footsteps sounded around her, something making a plastic-y sort of noise before he approached again, murmuring in her ear about how they would try different things to find what she enjoyed most. Based upon that book Hiccup had dismissed, Valka was expecting pain. Instead, something ice cold touched her back, something she thought should be melting but it just kept leaving frigid trails over her skin, sending shivers down her spine, throughout her whole body. Her nipples swelled in response to the chilled feelings despite Hiccup staying on her back, and Valka dimly hoped Hiccup didn't notice before the ice swept across the dip at the base of her spine and her whole body bucked, knees almost giving in shock.

"So that's a yes on the ice, I take it?"

A shuddering, half-nonsense noise that was supposed to be "yes" left Valka's mouth, still trying to catch her breath from that sharp spike of feeling, unsure how she was still standing. Hiccup's fingers touched her next, rubbing and stroking.

"W-what are you doing?"

"Warming your skin back up."

His hands were warmer than her chilled skin. And the touch felt quite nice. Both hands moved over her back, chasing away the cold until his fingers curled loosely around her waist, his breath warm against her shoulder.

"What next? Heat? Pain? I even have something that could make you squirm until you can't breathe if you're particularly ticklish..." his fingers scrambled over her sides, and Valka bowed and wriggled at the very ticklish touch "aha!"

"No tickles!"

"As you wish. Back to the question. Heat? Or pain? Neither will leave lasting damage, I promise."

His hands were still on her. Valka wondered if his gentle strokes over her hips were intentional.

"I'll try both."

The chances Valka would ever have the nerve to do something like this again - with anybody, she'd obviously not come back to her son! - was pretty low, so if she was going to experience these things, it ought to be now.

"Alright then. I'm going to take off your bottoms, if that's ok with you?"

She felt utterly naked when he did, though Valka still had her bra and pants on. Hiccup had to hold her as she stepped free of her jeans, then led her toward the bed - his bed - before laying her down, moving Valka to how he wanted her and so she could still breathe. Her ears picked up the sound of a match striking, a few hissing noises before Hiccup blew the match out, that distinct scent lingering in the air afterwards.

"Don't forget to breathe."

Valka let out a breath she hadn't realised she was holding, heard the scrape of something against something else, before she could smell... chocolate?

Warmth splashed across her back, not the heat she was expecting but there was something about the buttery liquid that made her whole body go lax, the drips unpredictable as they were drizzled over her skin, dribbles landing over her arms as her wrists were still bound behind her. There was a faint ache in her shoulders, telling Valka she'd been slacking on her yoga as it shouldn't really have stressed her joints so much already.

The wet, moving muscle was distinctive, and Valka realised Hiccup had licked chocolate from her skin, continuing the journey until his mouth was hovering over the base of her spine, lapping up the puddled liquid there. She wasn't sure if she should question it. Hiccup had said it wasn't sexual... maybe the warmth of his mouth was part of it?

Either way, Valka ignored the mental images of him knelt above her, body oh so close...

A damp cloth swiped away the sticky mess left behind, but it wasn't enough to erase that tingle left by Hiccup's tongue.

"Don't tense up now."

Valka tried to stay limp, but her whole body jerked with the first splash of what she knew instinctively was melted candle wax, every nerve in her body seeming to rush to that little spot that was on fire... but only for a few seconds, the burn fading to a pleasant sort of heat afterwards. Then the next came, and the next and the next... Hiccup alternated between single drops and steady drizzles, up and down her back, moving to the back of her thighs when he seemed bored of one spot and Valka squirmed anew as she cursed thoughts of his tongue chasing melted chocolate there...

Strangely, Hiccup's fingers ran over her cheek for a few seconds, then retreated. Before Valka could think too hard, there was wax running between her thighs as Hiccup left a burning line there, mattress rising as his weight vanished again.

Her whole body was trembling slightly now, and Valka realised with a horrified thrill that despite what Hiccup said about BDSM not being synonymous with sex, she was obscenely aroused already. By her own son.

"I'd just changed those sheets. Ah well. Mess is inevitable."

His hands set about removing the dried wax from her, quick and efficient and her skin felt oddly smoothed beneath each disc. Fingers rubbed the inside of her knee, seeking to soothe Valka slightly.

"Are you alright? You're shaking."

"I'm fine" I'm horrifically turned on by you, but I don't want to stop "keep going."

"Do your shoulders hurt?"

They did, but Valka was too enthralled by her own vulnerability to let him free her yet.

"No."

"Hands feel ok?"

He pinched her fingertips anyway, but Valka answered to be sure.

"Yes."

"Good. Now, there are different types of pain. Lots of types. I won't show you them all at once, else I don't think you'd be sitting very comfortably for a few days. But based on what I've seen from you so far, I have an idea for what types of pain you will enjoy. If I'm too rough, say red. Not rough enough, say green. Just right and you want me to stay that intensity, say yellow. Understand?"

"Understood."

"Alright then. I'm going to lift you a little, don't panic."

He lifted her hip, sliding a thick pillow beneath and Valka flushed lightly when she realised the angle he'd shifted her to meant her backside was now rather... pointed up. On display. Hiccup opened a door, his own breathing quicker and heavier than earlier... or was that Valka's own? It was hard to tell now, turned about and turned on as she was. His footsteps came closer again, stroking just above her waistband.

"Ready? This is only to find your level, if you don't like it, say so and I'll get something else."

"R-ready."

Gods, she was wet. Valka really hoped Hiccup couldn't see. She didn't know where he was standing, if it was clear, or if he could even tell from her squirming.

The sound of something passing through the air hadn't yet registered properly when the impact did; it wasn't agonising, or even painful, but the shock of something landing square against her ass was enough to make Valka cry out. Like the wax, the sting made way for a lazy warmth, one Valka was sure could grow much hotter if the fire was fed just right.

"Well? Red, yellow or green?"

Oh. Right. She had to tell him.

"Green."

The next swing was a little harder, but still not enough. Valka hadn't known she would want the pain, the sting, the ache... but now she had it, she needed more.

"Green."

Three more times he hit her harder before Valka felt it, that sweet, perfect mix of sting and fire that sent violent waves of pleasure rolling through her body.

"Y-yellow."

"Got it. I want you to count down from ten. If you miss one, I will start again."

His voice made her shiver. Valka knew logically she could use her safeword, make it stop. And as she grew hotter and wetter, Valka knew she should. But already she was hooked, desperate for more.

Smack! "Ten!"

He managed to hit the exact same spot, the sting more intense, the fire left behind for longer. Valka shuddered as fresh arousal washed through her.

Smack! "Nine!"

Her breath was ragged, body twitching with the constant pulsing left behind after each impact. Hiccup alternated sides, swats five and four landing a little lower on her sit-spots before coming back up.

"Ah-ah. You forgot to count number three. Guess we'll have to start over."

Valka wasn't sure if she was going to come or cry. Maybe both. Her ever-diminshing brain power was struggling to remember what numbers even were anymore. It took whatever self-control was left to not simply beg her son to pull down her soaked pants and fuck her stupid. She bit the blanket beneath her in an attempt to process the second round of swats, grunting out the numbers and that seemed to pacify Hiccup enough that he didn't start over. Even that wasn't enough though, not when his final two impacts hit her harder, the crack! of stinging pain against glowing red skin too much for her. Dignity utterly gone, Valka bucked and sobbed and twisted, writhing through the waves of climax and knowing it was impossible Hiccup hadn't noticed that.

The surging hormones left her brain in a haze, and when Valka came to her wrists were free, Hiccup's fingers petting her hair and his voice making a series of soft, soothing noises to bring her down. She'd never known anything like that, the intensity of a pain-induced orgasm far superior to anything she'd felt before.

"Hey, hey, you're alright."

Hiccup was trying to calm her. Valka realised she was still shaking, using her tingling hands to seek purchase and anchor herself to the reality of cotton sheets beneath her, seizing that and using it to pull herself back to reality.

"Back with me?"

"Uh-huh."

Words were beyond her for the moment. Valka reached up and pushed the blindfold off, hoping the regained sense would help balance her others, nerves firing and blood pounding in her ears. Blinking until her eyes adjusted again, Valka could see the dark material of black jeans, Hiccup's leg closest to her as he sat next to her, waiting for Valka to come down.

"Is that... normal?"

"I've never had a submissive come from just being spanked, but if you mean the whole floaty brain-melting, yeah. It's called subspace, and it is a result of all the chemicals rushing around at once. I didn't think to warn you, because, well, I wasn't expecting you to be quite so responsive. That was remiss of me as a Dominant, and I am sorry."

He was apologising? For that? Valka almost laughed.

"It's... fine. Gods..."

"Don't roll over yet. I need to treat your skin first."

Valka didn't immediately click on to what he meant, but Hiccup was soon kneeling behind her on the bed again, rolling the elastic band of her underwear down and she ought to be embarrassed, but after seeing her come Hiccup ought not to be surprised by the wetness there and Valka was still too blissed out for shame yet.

"Breathe, this might be cold."

He wasn't wrong, the gel-like substance on his fingers definitely chilly against her burning backside. Hiccup massaged it across her skin as though he'd forgotten entirely that she was his mother, and judging by the firm length pressing to the back of her thigh, Valka would bet he was not as unaffected as he appeared.

"What is that?"

"Aloe. It encourages healing and ought to take away some of the sting."

It felt nice, cooling and easing some of the residual sparks of her nerves. His movements were methodical, no lingering touches even as he pulled her underwear back up, though Valka heard his sharp intake of breath as moving off her in those jeans that hugged an erection undoubtedly strained him a little. Even with his aftercare, Valka still hissed when she rolled over.

"That'll pass."

Valka nodded, wriggling and shifting until her weight was more on her hips and back than her ass, which helped the pain but not the urgent arousal that resurfaced with the fresh contact against what transpired to be an incredibly sensitive part of her body. It was that more than anything that made the decision for her, taking in Hiccup's swollen groin and dilated pupils, the flexing of his hands by his sides and pushing her hand up along his inner thigh.

"What do you want mom?"

It ought to have sickened her, reminded her that everything was so very wrong there, but hearing him call her "mom" only thrilled Valka further, urged her hand higher.

"You."

-HTTYD-

I'm leaving this as unfinished because, well, it's obviously not done. However, I offer no guarantees for when it will ever get done.