This was a weird idea that came to me at 2 am. I dwelt on it enough that I thought 'ya know, I can make this work.'

—

Takes place during the last season of RTTE. And 6ish months before the first film. I highly suggest looking up AJ Kane on Youtube and listening to his intro video. He's playing kid Hiccup in HTTYD3 (we think).

—

"Alright, that's a bushel of red oleander, a pint of honey, a tablespoon of Monstrous Nightmare gel, 4 sticks of cinnamon, and a pound of ground squirrel bones. Is that it?" Hiccup looked over the ingredients they had gathered.

He and his team, along with Gobber, Stoick, and Gothi gathered in the Great Hall, looking over the sick patients who had been quarantined here. There had been another outbreak. Another sickness that was taking villagers, and making them cough, vomit, and bleed from their noses before putting them into a coma-like sleep. Thankfully, no one had died yet, but it was only a matter of time. And more and more villagers came up to the Great Hall with rags covering their noses.

They had to find a cure.

Luckily, Gothi was something of a witch in that regard. She looked over the ingredients the kids had gathered, took just a bit, and crushed it into a paste with a mortar and pestle. Then she fed it to one of the sick patients.

He didn't even stir.

Gothi frowned, her wrinkly mouth screwing up in a flurry of lines. With her staff, she wrote in the dirt.

"She says, there's one ingredient she's missing, but she was hoping she didn't need it," Gobber read.

"Well, what is it?" Urged Stoick.

"North Swamp Flightmare Algae."

Hiccup frowned. "Well, it'll take a day, but there's another island with the algae we can get."

Gothi smacked him in the head and underlined 'North Swamp' on her note.

"Ow! Yeah! I get it! But there's not any Flightmare Algae in the North Swamp. We let it all out to sea years ago to get rid of the Flightmare."

Gothi was writing again, her eyebrows furrowed.

"She says…then we'll have to go back to when it was there."

Everyone looked at each other, and then back at the old woman.

"Have you finally gone Senile?" Hiccup blurted out. That earned him another swat.

"Yeah, I deserved that one."

Gothi didn't elaborate any further as she beckoned them up to her house.

—

Astrid, Hiccup, Stoick, and Gobber all awkwardly crowded in her little hut as she walked around, flipping pages in books and going through jars of what just looked like dust.

"Are you going to explain yourself anytime soon, Gothi?" Asked Stoick.

She glared at him, and then continued her work.

A large, full body wash basin was pulled into the middle of the room from a corner, and Gothi handed out buckets to her guests, and then pointed outside.

"You want us to fill up the tub with water?" Hiccup guessed.

Gothi nodded once, happy to see he picked up her request quickly.

A few trips down the mountain and back, the tub was mostly full.

Still quiet and aggravatingly mysterious, Gothi added a mixture of dusts to the water. Finally, she yanked on Hiccup's hand and plucked a lock of hair from his head and dropped it in the liquid. The water illuminated a bright purple, and sent off sparks, startling everyone. Smoke began to billow out and fill the room.

"Is…this normal?"

When the smoke subsided and the water returned to being clear, Gothi finally explained her plan.

Gobber read from her scratching. "She says, she's made a potion that will switch present Hiccup with past Hiccup so he can get the Algae."

"Whoa whoa whoa wait, what?!" Hiccup shouted.

She scribbled some more.

"If you lay in the water, you will go to the past and replace the version of you that existed back then."

"Are you seriously talking about time travel!? Nuh huh! No way!"

She whacked him again and again. "Okay okay! Gods, why me?"

Astrid shrugged with a little grin. "Maybe it's pay back for the time you slapped her and set her on fire."

He grimaced. "That was an accident! I would never-!" His voice cracked in desperation.

But Gothi was writing on the floor calmly.

"She says…she picked you because you need it."

"I…what? Why?"

She didn't write anymore and Gobber shrugged.

"How…how many years am I going back?"

"Five."

Silence took the room as everyone digested that information.

"That's…that's before Toothless." Astrid said.

Hiccup had his eyes closed, painfully. "I really don't want to go back to that."

But Gothi wasn't giving him a choice as she tugged on his hand again and started undoing his armor. He got the message and undid the rest by himself, just leaving the thin shirt he wore under everything. She tugged that off too. She went to a table in the corner, and mixed up a paste. Then she returned and drew a sigil with it on his chest and on his forehead.

Finally she wrote some more in the dust. "I'm returning you to a time when the algae still remained in the North Swamp. You will have three days to collect the algae and return."

"And how do I do that?"

"After 3 days, fill a water basin and submerge yourself. We'll send the younger you back the same way we sent you."

Hiccup looked to his friends and family. "Are we really doing this?"

Astrid grabbed his arm and kissed his cheek. "You'll be fine. Gothi wouldn't do this if it wasn't safe."

Gothi nodded once and confirmed in the dirt. "You have already done this, but your memory of it disappeared after your return."

Hiccup was smart, and understood that if they were going to the past, then he would have remembered coming to the future 5 years ago. It made sense, even if Gobber was just scratching his head in confusion.

"Alright…if this is what we need to do to help the village, then I'll do it."

"Good on you lad."

Gothi beckoned him to the tub, and he climbed in. For a minute, he just sat there, wondering if it would work or not, before the water glowed purple again.

"Wish me luck!"

Gothi pressed a hand to his face and dunked him underwater. The potion flashed and smoked, but only a few seconds later, she brought him back up.

Well, sort of.

A much younger and smaller Hiccup coughed and sputtered as he broke the surface.

"What?! Where?! How!?" He shouted, in a much younger, prepubescent voice. "Gothi? Where—?"

He glanced around the room, noticing the group looking at him with awe, and ducked down into the water a little more. "Dad? Gobber?" Then, he looked at Astrid. Confused and doubtful, he managed a quiet, "…Astrid?"

She smiled at him. "So you do recognize me."

His eyes bugged out of his head. "One minute, I'm taking a bath and then next…" He put his head in his hand, disoriented.

"How old are you, Hiccup?" Asked Gobber.

"I'm…14?" He said, with uncertainty.

Stoick reached down to pull him out of the water, but Hiccup surged forward and covered himself with a blush. He was very naked, having been bathing prior to this.

Astrid turned away with a little giggle.

Gothi had mercy on him and dropped a towel on his shoulders as he climbed out of the tub. "I still don't understand…did I do something wrong? Was I hurt? Have I been unconscious?" Hiccup looked up guilty at his father.

"No no, son. You didn't do anything wrong." Stoick wrapped the towel around him a little tighter and rubbed his arms.

Astrid turned back around, but said nothing. Her eyes were drawn to his left leg, which was still in one piece. Of course it was, this was before the dragons, right?

Looking at him standing next to Stoick, she was struck by how small he was. Of course she remembered him being tiny, and always shorter than her. But she had grown up as well, and now he looked so fragile, she was afraid to breathe on him.

Little Hiccup looked around, terrified and very confused.

Stoick spoke to him, softly, which seemed to scare him even more. "Thanks to Gothi, you've been sent 5 years into the future. Our Hiccup had to go back and find something that doesn't exist anymore. So you've switched with him for a bit."

Hiccup said nothing, only looked between those gathered, and did the only logical thing.

He screamed bloody murder and passed out.

—

Five years ago, Big Hiccup surfaced in his home bathtub, sputtering and coughing. He hadn't expected Gothi to shove him in the water like she had, so he had inhaled a bit of fluid on the way down.

"You okay in there son?" Stoick called from the other room.

"Yeah, dad. I'm fine."

Hiccup felt the house shake before the curtain flew back suddenly. Stoick was there, wide eyed, and staring at him.

"Hiccup…?"

"Hi," he smiled.

"You…" Stoick looked him over, his mouth fighting for words. It was definitely his son, he'd know those eyes and big nose anywhere…but he was so big now…"I've heard of boys going through puberty overnight, but this is ridiculous."

Hiccup couldn't help but laugh as he stood. "Sorry, uh…this is going to sound weird, but I'm Hiccup from five years in the future. Gothi switched me and your Hiccup so that I can get something that doesn't exist in the future anymore."

"You mean to tell me that old hag is behind this?"

Hiccup grinned again and actually stepped out of the tub, good foot first. "Well, yeah, but it's for a good cause. You see, Berk gets sick and we need to—"

Stoick choked suddenly.

"What's wrong?"

"Son…what happened—your leg…"

Hiccup glanced down at his metal foot. "Oh that? That happened years ago. You see, I killed a dragon—" He didn't get to finish his story as Stoick promptly passed out on the floor.

—

Now dressed, in clothes too big for him mind you, Little Hiccup sat in Gothi's hut while everyone explained the situation to him again, slower and gentler this time.

"So…you're saying that 19-year-old Hiccup needs an ingredient for a cure, and the only way to get it is to take my spot in the past?"

"That's right," Astrid confirmed.

"Then, what I am supposed to do in the meantime?"

She rested a calming hand on his head, watching as he blushed several shades. "I guess you'll just have to hang out with us."

"O-O-okay…" He shrugged, trying to be cool. Internally, he was freaking out. How close was Big Hiccup to Astrid?

"We should go back to the others at the Great Hall and let them know what's going on."

"Others?" Asked Hiccup.

"The other riders, Fishlegs, the Twins, and Snotlout."

Hiccup recoiled. "I don't want to see Snotlout, he hits me." Then he whirled on his dad. "And I know it's a viking thing! And that it shouldn't bother me! But I still don't like it!"

Stoick looked a little put off, and then smiled, and twinkle in his eye. "You don't have to worry about Snotlout, son."

"Yeah," Astrid smiled. "He can be a jerk, but he hasn't been a bully to you since—" Since the Red Death. But they couldn't tell him about that. That would totally freak him out. "Since you grew taller than him."

Hiccup looked surprised. "I grow taller than Snotlout?"

"Taller than all of us, except your dad. You're over six feet tall."

Hiccup scoffed. "There's no way…"

Gothi crossed her arms with a little huff.

"Oh, I think she's telling us to get out."

Hiccup stood, and hiked up his pants. Then he followed everyone out to the deck, before he saw a black dragon staring at him.

"Ah!" Hiccup shouted before diving right back into the shack.

Stoick laughed. "Ah, it's okay boy-o, Toothless isn't going to hurt you. He's your friend."

Hiccup peeked out the door with wide, disbelieving eyes. "Did-Did you just say…that he's...a dragon, is my friend?"

"Aye! It's Toothless!"

Astrid wasn't sure how they were going to explain Hiccup's sudden change to the dragon. But it turns out, he didn't care.

Toothless sniffed the frightened boy and decided that, yep, this was Hiccup, he must have just shrunk in the wash. He nuzzled and purred, and crooned. And then licked his face.

"Gah! Wait! Stop! That tickles!" Spit dripped off of him after Toothless let go. "Eww…"

Stoick patted Little Hiccup on the head as he spoke to Astrid. "We'll meet you two down at the Great Hall. Why don't you give him…a little tour of the island?"

Astrid smiled mischievously, and turned to the dragon. "Now Toothless, this Hiccup doesn't quite know you, so I'm going to be piloting you, okay?"

Toothless looked put off and whined at Hiccup.

"Don't look at me! It's not my fault!"

Astrid mounted the saddle and clicked out the auxiliary line for other riders in case of emergency, then she offered her hand. "You coming?"

"We…We're flying?"

"Duh! Come on!"

Gingerly, he mounted the saddle behind her and she placed his arms around her waist.

"Ready?"

"As I'll ever be."

Toothless took that as a launch request and took off into the air.

Both riders screamed. Astrid, in exhilaration, and Hiccup in pure terror.

"Oh Gods! I'm dying! I'm going to die! This is the end!"

Astrid couldn't help but laugh. In less than a year, his time, he'd be doing this exact thing to her younger self.

This was revenge, wasn't it? A sick revenge that she'd never get to pull without this weird time swap.

"AAASSSSTTRRRIIIDDDDD!" He cried. "I'm gonna hurl!"

And in two soft pats, Toothless evened out to a serene, gentle glide. Hiccup dry heaved and slowly caught his breath. "Gee. Thanks."

Still the sarcastic little shit, she mused. "Sorry, you usually enjoy flying like a maniac."

"Well, maybe I get a stronger stomach in the future." He rested his head on her back, too sick to be ashamed. She just patted his hand in consolation.

"I'll take it easy from here on out, then."

Hiccup took in view. They were so high, it was dizzying. He shut his eyes and hid his face in her back again. It was too much.

But then, he inhaled, and smelled the sweet fragrance of her hair and her clothes. She was so soft to lean against, to hold around the waist. So soft and warm…he smiled.

"Uh, Hiccup? Whatcha doing there?"

What was he doing? Oh. His hand was totally groping her breast.

"I'm sorry!" He screamed, and let go of her entirely. The sudden action made him lose his balance and he fell right off the saddle with a scream.

Astrid scoffed with a little grin. "Boys."

—

Big Hiccup got a cold wash cloth for his dad.

"Thanks son."

"No problem," Hiccup said with a smile. He glanced around his childhood home. A lot of things changed in 5 years, sure, but he had forgotten how many weapons and dragon remains decorated the house. It was gruesome and sad.

"Now, about this dragon…" Stoick began.

Hiccup held up his hand. "Look, Gothi already told me you're going to forget about everything that happens while I'm here. So, I could tell you, or you can find out in…oh, a little less than a year from now."

Stoick frowned hard. "That soon? Why, you're still such a tiny thing…"

"True. Though by then, my voice will have changed…"

"…what kind of dragon is it?" Stoick didn't even try to mask the excitement in his voice.

Hiccup grinned. "We call it the Red Death."

"Hmm, never heard of it before. Small and poisonous, is it? Had to amputate your leg to save you?"

Hiccup laughed. "God, I wish. It's…hold on, where's my sketchbook?" Hiccup trekked upstairs and stared at his room, Toothless' slate wasn't there. Of course it wasn't. Toothless was off flying somewhere. Flying with two intact tail fins…

An idea struck him suddenly. He was in the past. He could make sure that Toothless never lost a tail fin, that he never shot him down…But to live the rest of his life without him? Hurting Toothless had…it had fixed everything in the end. Without him, the raids would continue on, and he'd never get respect from his father, he'd never get close to his friends…and he'd never get Astrid. And that's what started this whole thing after all, wasn't it? Killing a dragon to get the girl.

He heard the steps creak behind him. "I think he-you, you left it on the desk." Stoick said softly.

He hadn't noticed he had just been standing there until Stoick spoke. Sure enough, that familiar black book he had so many years ago sat on the desk. He picked it up, along with a charcoal piece. He glanced at the other items on his desk, a chill going down his spine. Schematics for weapons, dragon slaying weapons. Dragon bones. Drawings of dragons being impaled with swords and arrows, with red 'x's on them labelled 'die' and 'kill'.

Gods, he was obsessed back then. But who could blame him? Everything was awful, and killing a dragon was the only chance for redemption he had. He was so convinced that was the only thing that could make his life better…and in the end, he still had to kill the Red Death. Didn't he?

"Hiccup…?" Stoick asked again, fearing the worst.

"I'm fine…" He said, turning to face his father. The father that had the hardest time loving him and seeing him as his son instead of a thorn at his side.

"Oh, ya say that, but the tears running down yer face say something else. Are you in pain? Do I need to get Gothi?"

Hiccup rubbed his cheeks with his hand. "No, no…I'm fine. I just…remembered what it's like for me here."

Stoick frowned. "Aye, it's a bit rough. Being so small around people that just like to punch each other. But look at you now! Tall and strong! And ya even match Gobber!" He spoke proudly, obviously in love with the future he saw.

"It's not glamorous," Hiccup corrected. "I lost everything before this fight. You disowned me even."

"Disown you? Why would I do that? I mean, sure you can be a little reckless and troublesome, but nothing worth disowning you over."

"You disown me because I save a Dragon, train it, and have it as my best friend."

Stoick stared, open mouthed before he yelled. "YOU WHAT!?"

Hiccup barked a laugh, "I knew that was going to be your reaction."

"Why? Because it was the same before?!" The chief's anger was boiling. "Befriending a dragon! You've got to be joking! What kind of idiot do you take me for? What kind of idiot are you!? The mere thought of—"

Hiccup crossed his arms. This could be a while.