Hiccup has XX Male Syndrome (and here's why)

-XXM-

An "Adam ruins everything" exploration of Hiccup Horrendous Haddock the Third's family tree, and just why he's so unlike most Vikings.

-XXM-

"I think you're missing the point though. I mean, Chief! What an honor! I'd be pretty excited!" Astrid was indeed excited, almost making up for Hiccup's lack of enthusiasm.

"I- I'm not like you, Astrid. You know exactly who you are; you always have, but… I'm still lookin'." Swinging his arms in exasperation, Hiccup bent over to pick up his riding helmet. He straightened again, resuming his explanation as he strolled toward the vista of Itchy Armpit. "I know that I'm not my father and I never met my mother so…" He looked down at his feet, then collapsed into his rear by the edge of the cliff. "What does that make me?"

Astrid sidled over, preparing to sit down next to him. Suddenly the dragons squawked in alarm. At the same instant, a deeper but lightly accented voice rang out between them and their dragons. "It makes you a helluva complicated character to write about, that's for sure!"

Astrid spun around, reaching for her axe but grasping empty air. Hiccup leapt awkwardly to his feet, stumbling away from the cliff edge. Standing unperturbed between the humans and their dragons was a teenager, somewhat resembling a cross between Snotlout and Fishlegs, wearing clothing that seemed in impossibly good repair.

"Wha- what in- who are you and how did you get all the way up here?" Hiccup demanded, still very confused. The stranger around in muted appreciation, taking in the many beautiful sights of Itchy Armpit.

"I'm Matthew, FanFiction author from the distant future, relative to you two. I got up here because I have a pretty specific topic I want to explore, and this scene is the perfect point from which to do it. Well, maybe not perfect, but certainly less embarrassing than my first idea-"

"You're from the future?" Astrid cut him off, incredulous.

"A future, not the future. Specifically, not your future." Matthew corrected. Toothless walked up behind the time-travelling interloper, clearly suspicious of his sudden appearance. As if clairvoyant of the dragon's silent approach, Matthew turned around. "Hey there Toothless. You're- wow, You're surprisingly big in person."

Hiccup shook his head, uncomprehending. "You're from a future and you just appeared here to… what, exactly?"

Matthew turned back to the dragon riders. "Ah! Oops! Getting distracted. Best get on with this. Short version: you two are dating, that's great, but: newsflash! Hiccup is sterile."

Hiccup blinked, his face slack from the time traveller's sudden statement. Astrid grew furious. "He's what?! How could you possibly know that?"

"Well, first off, I'm from the future. I can view any point on your timelines and alter your lives however I want, because of a whole lot of complicated cultural changes in my world I won't even get into right now. The important thing I'm bringing from the future, though, is a strong grasp of medical science. Specifically, some fields known as genetics and genealogy."

"Now, hold on, why do we have to listen to a word you're saying, strange time travelling person who-"

Matthew shrugged. "There isn't any need for you to listen, I'm just giving you friendly warning about how my headcanon will affect my view of your lives."

Astrid tilted her head. "Head what-now?"

"We're veering off topic. Hiccup, you have what the future medical community calls Male XX Syndrome. Your tribal elder probably would refer to it as a curse."

Hiccup shook his head. "I have absolutely no idea what 'XX' or 'Syndrome' means."

"As I expected! So, a brief primer on biology. The human body is an incredibly complex structure. All of that complexity is written in these little tiny things called chromosomes. Chromosomes have uncountably many letters in them, in a code we're only beginning to understand, but one important thing to note is that most normal humans only have forty-six of them." As the time-travelling interloper spoke, strange glowing shapes and glyphs in a language Hiccup and Astrid couldn't read floated in the air around him. Toothless and Stormfly became less wary, sitting down and watching the light show with confused interest. "Of these 46 chromosomes, the gender of humans is decided by two of them."

Hiccup and Astrid both blinked at the pile of new information thrust on them. Hiccup, the more mentally active of the two, came to a question first. "G-gender? As in whether someone is a guy or a girl?"

Matthew nodded. "Quick study. Yep. There are two variations of these chromosomes. XY for males, XX for females. There are, of course, glitches along the way. Many significant birth defects are caused by just X or XXY, or XYY in the case of over-fertilization."

Astrid blinked. "Didn't you just say Hiccup had XX something-or-other? Shouldn't that be for guys?"

"Very good Astrid. XX is almost always for female, except in very rare circumstances like Hiccup's."

"So let me try to get this all straight," Hiccup said, "chromosomes are like books with all the information about a human stored inside. There are forty-six books, and only two of them decide whether someone is like me or like Astrid, gender-wise. You're telling me I'm some weird case where I have all female books, yet I turned out male? It's going to take a lot of convincing to explain that to me."

Matthew turned and began walking toward a flat rock on the ground. "And that's why I've left this here." Matthew bent down, lifting the stone to reveal a hole in the ground disappearing into inky blackness. "Shall we go see how the books got mixed up?"

"You tell me my boyfriend-" Hiccup blushed at her use of the word. "-is actually not a boy, and now you expect us to just jump into a strange hole in the ground-" Astrid began, clearly skeptical.

Matthew leapt into the hole, disappearing after only a moment into the dark. His voice echoed back from far away. "I couldn't care less if you followed, but you make things more interesting for the viewers."

Toothless sniffed the edge of the hole, then looked up at Hiccup. Hiccup shared a glance with Astrid. She was clearly pleading for some kind of explanation. His confusion told her he had none to give.

"If none of you are coming, I'm going to drag the perspective down here!" Matthew's voice echoed up, now further away.

Toothless yelped and leapt into the hole. Hiccup looked after him, then over at Astrid. "Fine, whatever, we'll follow the crazy person and your dragon!" Astrid conceded.

The two of them hopped into the hole, falling down, down, down… seemingly endlessly. After an indeterminate period of time, they felt a force slowing them like a soft breeze, getting more viscous over time. As they finally came to a stop relative to the strange air, they found themselves in a large space, the walls they could only dimly make out with a red glow in the distance. Not a few yards away Matthew floated in space, Toothless swimming through the air and gurgling happily around him. A moment later, a squawk of alarm announced the arrival of Stormfly.

"What- where?"

"To answer your very articulate question, Hiccup, we are inside your father's so-called 'family jewels,' roughly a day prior to your conception."

Astrid looked perplexed. Hiccup shook his head in confusion. "How-"

"I'd explain it, but the short version is that it simply isn't possible. So, focus on the lesson now. The walls of this tube are producing sperm cells, each one of which contains twenty-three of the necessary forty-six chromosomes necessary to describe a full person. The one that will eventually meet up with an egg cell in Valhallarama to create Hiccup is going to emerge in about a minute right over… there." Matthew pointed to one of the distant walls.

"So are you going to magically pull us over there now?" Astrid asked.

"Nope! Your dragons will fly us there." Toothless and Stormfly swam through the air up behind them, nudging underneath their riders' legs (or leg) until their perplexed humans slipped into the saddles. Toothless shot forward first, gripping Matthew by an upper arm. "Woah, careful with the dress shirt Tooth'."

"Toothless, bud, are you okay?" Hiccup asked, concerned by his dragons' sudden obeying of a stranger's wishes.

"Toothless is fine. I just suspended the dragons' free will for a bit for plot purposes."

Astrid went livid. "You did what?! How dare-"

"Oh! Look, we're here." Matthew cut her off as the shifting, red glowing wall loomed ahead of them. The dragons coasted to a stop in the viscous air surrounding them, and Matthew freed himself from Toothless' talons to swim a few paces closer. "See, now, that cell there is about to undergo meosis. It'll create copies of all the chromosomes, separate the copies, then pick half the books for each side of a second separation producing a final count of twenty-"

"Twenty-three chromo- things. We get it." Hiccup cut off Matthew, clearly impatient with the stranger's madness, but perhaps a little curious. "Why do these 'cells' take such bad care of this incredibly important information, exactly?"

Matthew shrugged, bobbing up and down in the viscous air. "Up to a point, mistreating the information is actually a good thing as there is a chance that the information will get more accurate, or better than accurate."

"What if it breaks something important?" Astrid asked, clearly not following.

"That's a whole thing called evolution that won't be discovered for around eight-hundred years. For now, just go with it. In addition to tossing around chromosomes like water balloons-"

"Water what?" Hiccup interjected. He was ignored.

"-The cell also intentionally swaps pages and even entire chapters between the books in a process called crossing over."

"Why?!" Astrid shouted, frustrated with the explanations going right over their heads.

"Mixing around information means that over time you end up with backup copies. It might not make sense, but believe me that it works."

"I really don't believe it, but please, continue." Hiccup muttered.

"Now, one of the genes, or chapters in the book analogy, that makes the Y chromosome create male people is the SRY gene."

"What does the chapter say?" Astrid asked, hoping for a straight answer.

"In a literal sense, it's the letters A, C, T and G repeated over and over in different patterns. Genetically, it describes how the male reproductive organs are made."

Astrid leaned back on Stormfly's back, disgusted. "So it's a chapter written only in four letters all about guys'-"

"I think you've taken the book analogy a bit far. Let's get back on topic." Matthew cut her off.

"So, what does this have to do with me? The topic was me and that male… XX… whatever, right?" Hiccup asked.

"Good question. Yes. We're actually just about to see it here… there! See how that chromosome has a longer left lower leg than most of the others'?"

Astrid frowned. "I see a bunch of dark shapes moving around behind a dark wall, all of them with funny lengths."

"The point is, that chromosome eventually ends up in the sperm cell that joins up with his mother's egg cell. It's an X chromosome, but it came away from that crossing-over with an SRY gene from a Y chromosome."

"So I've got a girl's book with a guy's chapter accidentally mixed in. Great. Can't imagine what I got from my mom if that's how I screwed up on dad's side. Not even born yet and-"

Astrid swung a punch at his shoulder, which landed very lightly in the viscous air environment. "Stop talking like that. You don't mess up like you used to anymore."

"She's right Hiccup, you developed a lot since the Red Death fight."

Hiccup shook his head. "So is that it? I mean, if I have the guy chapter, doesn't that make me a guy regardless of what the rest of the book says?"

Matthew hissed in mock sympathy. "Ah, afraid not. There are a lot of side effects to having competing chemical systems like this. C'mon, we've got more biology to learn now."

"So how are we going to travel now? Is some chariot from Asgard going to show up on your command?" Astrid asked, sarcastically.

"I could do that, but the viewer's willing suspension of disbelief would probably be shattered. Instead, I'll just teleport us to a presentation I gave in biology class, back in 2014."

"A what you gave in where? Was that a year-" Hiccup blinked. Suddenly he, Astrid and Matthew were standing in a small, cramped room with white stone-like walls that were impossibly flat. Humming boxes made of some kind of flat, dark metal sat scattered amongst white boxes made of various mixes of paper and hide. Sitting in a chair in front of one glowing box with various symbols flashing on its screen was a younger, less well-dressed Matthew. Their dragons were nowhere to be found.

Young-Matthew turned in his rotating chair to face them. "Oh. Hey future-me. Characters. This some kind of biology related thing you're writing about? I go on camera in about a minute."

Future-Matthew nodded. "Sure is, past-me. I need to skip to a specific point in this class though. The chemical cycles of the reproductive systems, in males and females."

Past-Matthew nodded. "Sure. Let me pull up this scrollbar that shouldn't exist until the class has been recorded and skip to that for you."

Astrid shook her head and stepped back. "This is school?! What are you learning from these- these glowing boxes?"

"These glowing boxes connect to other glowing boxes all over the world, so I and others can talk to each other in real-time, almost ignoring distance. Online high school is really great." Future-Matthew explained while past-Matthew manipulated a clacky thing in front of the glowing box and a small, black, glowing thing that vaguely resembled a rat.

Suddenly, another part of the glowing box lit up and past-Matthew began gesticulating wildly, talking faster than the ear could comprehend to the box. Eventually he slowed down to a manageable speed. "... The male reproductive chemical cycle is a negative feedback loop of Gonadotropin-Releasing-Hormone (or GnRH) triggering Follicle Stimulating Hormone (or FSH) release, which triggers spermatogenesis, which then triggers testosterone production. The testosterone produced triggers bodily changes such as musculature, voice deepening, and muscle production. It also provides feedback to the anterior pituitary gland to produce less GnRH, thereby slowing the cycle…" His voice returned to the previous inaudible speed, then slowed again. Hiccup and Astrid shifted uncomfortably on the strange, furry floor of the cramped space. Past-Matthew continued, having finished skipping ahead. "... The female chemical cycle is far more complicated. GnRH triggers release of both Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). FSH causes growth of the next ovary to ovulate. A spike in LH causes ovulation, then the newly released egg floats down the oviduct to attach itself to the uterine wall. The remainder of the follicular site becomes a Corpus Luteum, releasing large amounts of Progesterone to trigger the release of GnRH to cause the growth of the next follicle. If, however, fertilization occurred…"

Future-Matthew reached past past-Matthew toward the small, glowing, mouse-like object. "That's great old me, I think we get the point." The mouse-thing released a click, and suddenly the dragon riders and future-Matthew were alone in the cramped space.

"Were we supposed to understand anything that guy just said?" Hiccup asked.

"Where did he go?" Astrid asked, looking around.

"I skipped past the end of the recording. He's probably having lunch somewhere. As for that stuff we just watched, the point of it was the lengths of time each gender took to describe."

Hiccup scratched the back of his head. "What about them?"

"What about-" Matthew scoffed, "The female description was over twice as long in what we listened to, and that was only half of my past self's female presentation. The rest doesn't really apply - not to you - but the point still stands."

"And that has what to do with me?" Hiccup asked.

"All those complicated chemical systems from the female side are sitting inside you, sending out their signals and waiting for responses that'll never come from organs you don't have. That's kinda a problem for your biology. Worse still, the hypothalamus is listening for estrogen rather than testosterone, meaning your Gonadotropin-Releasing-Hormone feedback loop is completely ignored, and the testosterone generation continues at a flat level caused by the tiny spurts of LH from-"

"Now you sound just like your past self." Astrid complained.

"Right, sorry, dumb it down for the audience. Hiccup, this explains entirely why you aren't like other Vikings."

Hiccup shook his head. "You can't just point at your weird… gonodophin and say that I'm different because of that. What does any of that even mean?"

"Well okay, let me show you another approach." Matthew snapped his fingers and Hiccup and Astrid nearly fell over as the environment suddenly changed. Hiccup looked around and found himself in the forge, late at night. It was the old forge, from around the time he met Toothless, before many of his upgrades. A startled Viking kid in a green tunic and brown best nearly dropped the hot iron rod he was carrying with tongs onto his left foot. "Woah, young Hiccup, careful with that foot. We wouldn't want anything to happen to it."

Young-Hiccup stared up at the time travelling interlopers, mouth working but no sound coming out. Matthew filled the void with more incessant speech. "Right, so, future-Hiccup, you were always thinner than the other Vikings, right? Less muscle mass? Diminutive frame?"

"Well, yeah. I mean, I'm tiny. That's just how I am." Hiccup commented, shrugging.

"And on top of that, you were also more sickly, more often. Right so far?"

"Again, sure, but that's what happens with a smaller body. What are you getting at?"

"Without excess testosterone telling your body to beef up muscles and grow some assets the ladies would appreciate, you didn't. You withered away and became the Hiccup we all know and, let's be honest, totally enjoy having around."

"Wait, who enjoys having me around?" past-Hiccup asked.

"Oh, whoops, shouldn't have said that in front of this guy. C'mon, onwards!" Matthew led the two dragon riders out of the forge and up the village paths towards the great hall. Past-Hiccup stood, gaping at the departing time-travellers.

Hiccup jogged to catch up with the longer-legged stranger. "Onwards to what? This chemia- cheemia- whatever- thing you're describing in my body, sure so maybe I'm small and have a book of mish-mashed instructions. Who cares? I mean, it isn't like-"

Matthew pushed inside the massive doors of the great hall and Hiccup caught his breath, expecting at least one or two Vikings to be up this late hanging around. None were. Hiccup and Astrid jogged to catch up again in the darkness of the empty hall.

"Hiccup, I'm sorry to say it, but you're infertile. You're never going to have an heir." Matthew's voice echoing out of the darkness ahead of them was creepy. Suddenly, a bright light shone out from a dark, thin brick in Matthew's hand, illuminating a wall of the great hall. On the wall were five painted shields, depicting five happy chieftains and their sons.

"What's wrong with the shield wall? What does it have to do with Hiccup's supposed infertility?" Astrid asked, stepping partway into the beam of light from Matthew's strange brick to get a better view of the shields.

"Notice anything? I'm pointing specifically at Hamish 'Hiccup' the Second's sudden transformation into Stoick the Vast, but there's also another weird swap earlier in the line."

Hiccup's face fell as the realization hit him. "There's no shield with Hamish the Second as the father."

Matthew nodded, the light beam bobbing slightly. "Exactly. Chiefly succession carried down to a father's brother, or his son."

"So… both 'Hiccup the first' and 'Hiccup the second' were infertile..." Astrid whispered.

"Yep. That's the sad truth of the whole thing. Genetic predisposition of your family line to SRY crossing-over from the Y chromosome to the X chromosome." Matthew affirmed. "Anyway, I should get you two back to where and when you came from. Important plot still to come!"

Astrid rounded on him. "You just showed up to prove to us Hiccup is infertile, then you're going to leave?! What in Hel's-"

"Actually, didn't come here to prove it to you. I came here to explain it to a bunch of other people that will be watching our conversations over the same glowing boxes that I used to attend my online classes a year ago from my perspective. A few minutes, from our group perspective. About a thousand years from now for young-Hiccup's perspective outside-"

"What kind of monster are you?" Astrid spat. Hiccup was still looking at the shields, crestfallen and somewhat confused.

"One who does lots of research, has way too much time on his hands, and who totally dislikes how you two got together. Seriously, Astrid, you are so shallow. You ignore him for years then care about him after he trains a dragon and stands up for himself - against you? And, Hiccup, c'mon. She lets the other kids bully you for Odin knows how long, then when she shows the tiniest respect you decide to leap into her arms? Toothless cares more about you than she does."

Astrid's expression was blank fury as she sputtered incoherently.

Hiccup looked at her, then at Matthew. Then back at her. Matthew clicked a button on the brick he held, and suddenly the three of them were standing back on the cliff side at Itchy Armpit. Toothless and Stormfly gurgled and chirped respectively to welcome the riders back.

"S-Shallow?! I'll show you shallow! A shallow grave where you will never get a funeral pyre you son of Loki-" Astrid charged at Matthew, preparing to strike him. Hiccup stood uncertainly to one side, still trying to sort through his emotions.

"Actually, most people in my day tend not to opt for cremation. It's actually causing a bit of a land crisis, finding space for all the full-size graves."

Astrid stumbled to a halt, slack jawed in shock.

"That's not even the smallest change. On top of that, homosexual relationships and males that prefer to be on bottom are way more common, and publicly acceptable. Even now, in, umm… 1014, you're already living around someone fuðflogi, or as my English-speaking audience would know it, a man who flees the female sex-"

Astrid, regaining her composure, socked Matthew across the jaw. The interloper fell to the ground, and Astrid planted her foot in his gut, holding him there. "Who? Who in our village are you going to say some terrible thing about next?!"

Wheezing around the foot still buried in his gut, Matthew answered, "It's socially accepted and practically Viking law that every Viking must get married to another with whom they're capable of having kids. Yet, Gobber the Belch has been-"

Astrid pressed down harder on Matthew's gut and his coherent explanation turned into a wheezing gasp. Hiccup put a restraining hand on Astrid's shoulder. "Astrid, let's just leave him and move on. This- this is all a bit much for me to handle."

"Are you sure you two don't want to stick around? Bucket and Mulch are a pretty interesting couple, especially with Bucket's savanthood due to-" Astrid stepped off Matthew and gave him another sharp kick. The interloper rolled over, muttering something like, "Watch the dress shirt!"

"Fine," she spat, "I've had enough of his explanations to last a lifetime anyway."

The two turned to their dragons, hopping into their respective saddles and preparing to take off. Matthew stumbled to his feet. "Hold on, I do still need to talk about how dragons display clearly human-level intelligence in syntax and word-order understanding, even if they're limited by not having a human-translatable form of language!"

This stopped Hiccup. It didn't stop Astrid. "Wait, human-level? They can learn Norse?"

"Yeah, no kidding. Toothless understands literally every word you say. The other dragons are of more questionable intelligence, but it's likely Meatlug and Hookfang are just as smart. Probably also Windshear."

Hiccup stared at Matthew in shock. Astrid leaned over on Stormfly's back and punched the Hooligan heir in the shoulder to get his attention. "Hiccup, we're leaving."

"Right, sorry, I just-"

"The only other animal to show nearly that level of intelligence is the bottlenose dolphin, though they're unable to learn a spoken language, trials with trainers have shown clear and undeniable understanding of the grammar structure in a synthetic hand-signal language, sort of like exactly what Fishlegs taught you and your dragons four years back."

"Hiccup, ignore the guy spouting facts about dolphins and dragons and lets go!"

"Actually, pretty certain that was the last thing I needed to discuss. Now to get you guys back onto your plot and leave mine, you need to fly…" He turned around, looking at the gorgeous vista of Itchy Armpit. He pointed into the distance, between two mountains. "...that way."

Hiccup looked at his wrist-mounted compass. "Huh, was planning to fly that way anyway after I expanded the map, before all… this."

"Then let's get on with it!" Astrid demanded.

Matthew waved at them. "Have a good time!"

Stormfly took off and, reluctantly, Toothless followed. The dragons and riders left the time-travelling interloper behind, swooping off toward the two mountains.

"What a Loki-spawned Hel-servant munge-bucket bilge-rat of a-"

"Astrid, calm down! He's just some magic crazy guy who decided to ruin our lives by explaining things we'd probably figure out eventually anyway, or entirely ignore but spend a lot of effort ignoring. It's probably better that we know-"

"Better that we know what? That I'm 'shallow'?! That you're supposedly sterile?! That Gobber is ergi?! That dragons understand literally every word said to them?!"

"Well, I don't know about every word. He did say they were capable of learning the language, not that they already had." Toothless thwacked his arm with an ear plate, and Hiccup looked down in surprise. "So you do understand Norse?!"

Hiccup watched as Toothless slowly, condescendingly rolled his eyes at his rider.

Astrid was still fuming. "He called me shallow. Shallow! I've stood by you for years Hiccup!-"

"Five out of twenty." Hiccup muttered under his breath.

"-How can that stupid son-of-a-half-troll pile of yakshit just spit on what we have like that? I don't believe it. Not a word. Hiccup, we are getting married and we are going to have kids."

"What, I don't get a say-?"

"Why would you need a say?! This is what you wanted for years before I was talking… er, before the Red Death!"

"That was Astrid Hofferson, though. That wasn't… I dunno… you!"

"Oh now who's the shallow one?!"

"Astrid, that isn't what I meant… Gods that sounded really bad. Let me-"

Astrid threw her hands up, flopping backward on Stormfly's spine. The Nadder bobbed in flight. "So, what, did you ever care about me?"

"Astrid, you know I didn't mean to say it like that. I- I just say things and they're not always the things I really mean to say-"

She sat up again, staring at him. "Do you care about me or not?!"

"Yes!"

"Good!"

The dragons dropped closer to the Itchy Armpit forest canopy, clearly interested in something. Their sulking riders avoided each other's gazes, not paying attention to the environment. After maybe a half minute of quiet flight, Hiccup broke the silence. "Good? Is that all I am to you in all… this?"

Astrid balked. "No, Hiccup, I didn't mean it like that-"

Hiccup slumped forward on Toothless' head. "Is it always going to be this complicated or will we eventually figure this mess out?"

"We'll figure it out, Hiccup."

Hiccup rubbed his dragon's forehead, then blinked and looked up at Astrid. He looked down again. "... Good."

The two broke into good natured, awkward laughter, the sound echoing off the trees around them. Between his legs, Toothless hummed, but it wasn't in harmony with his rider's happiness. "Bud? What's wrong?"

Abruptly the trees ended, replaced by blackened stumps and trunks sticking into the air at odd angles. Not a speck of greenery existed past the first few feet of fire damage. Hiccup and Astrid looked ahead, spotting a column of smoke in the sky.

Hiccup looked back at Astrid. "Stay close. Seems we just found that crazy guy's 'plot.'"

-XXM-

A/N

Some of you are probably wondering: what is this? Well, this is my idea of some serious Hiccstrid bashing. Also, I am certain Cannon!Hiccup has this Male XX Syndrome issue, even if it wasn't intended by the screenwriters.

Now, of the evidence I presented, these pieces are questionable:

-The shields older than Hamish the Second's aren't visible in any recordings I could find, so I couldn't locate a "the First."

-Genetic predisposition to SRY crossing-over has not been shown to run in families. This is probably due to the phenotype of the genetic issue being infertile, and tending not to continue the family tree.

Of the evidence I presented, these pieces are (I believe) bulletproof:

-Hamish the Second is NOT Stoick the Vast's father, or Stoick the Vast's father's father. Red hair is recessive to most other kinds of hair coloration, so Stoick or Stoick's father couldn't have red hair if black-haired Hamish were their father.

-Hiccup has symptoms of XX Male Syndrome such as reduced height, weight and muscle mass.

-Hiccup has shown little active interest in his relationship with Astrid. He's accepting of it, (he really does care about her, and does what is expected romantically) but he's not really active in it or in pushing it further. Corresponds with XX Male Syndrome loss of libido.

As for the dolphin stuff, I'm sure you can Google that study up. It was really quite impressive. For the Viking societal norms and laws, my source is "vikinganswerlady gayvik. shtml"

Did I cherrypick my evidence to support my favorite pairing (Toothcup) and bash Hiccstrid? Absolutely. Do I care? Not really. Rate and Review however you feel. I'll just be home going through finals and rewriting my next FanFiction's Toothless character.

P.S.

The end of this oneshot was not an implication that HTTYD2 became a Toothcup because of this insane meeting with a FanFiction author. Rather, I left both Hiccstrid and Toothcup open for Hiccup to pursue as he sees fit. I may bash a pairing, but I'm not going to rewrite existing character emotions to make it fit! I'm not that cruel!

Though if I did extend Matthew's (the character's) influence throughout the story, he would do his damndest to make Toothcup happen. He (being me) is not that kind of author though. So… this was a thing.