Hey! This is my first fanfic ever, so please cut me some slack. So in the reviews, please give me some advice or something of that sort. This starts during the RTTE episode Dire Straits, Season 4 Episode 6. Hope you enjoy the story!
Chapter 1 - An Unexpected Occurance
Hiccup sank in his upside down bowl contraption, down to the bottom of the ocean. He reached the bottom, took a deep breath, and peeked out. The bottom of the ocean was mostly empty of visible life, except for the Submaripper chained to the bottom. Hiccup swam over cautiously to a chain, and poured the Changewing acid over it. It sizzled, and melted. He swam over to the next chain and quickly melted it. Hiccup retreated to his pocket of air at the bottom of the sea and took a deep breath. He dove back under and swam to the last chain, near the back leg of the Submaripper. He poured the Changewing acid on it, and then he heard a roar.
'Uh oh.' Hiccup thought, and turned around as quickly as possible as he could in the water. Unnoticed by him, the sinking Changewing acid, which hadn't reached the chain yet, brushed against his back. The rest of the acid reached the chain and melted it. The Submaripper had noticed Hiccup, and thought him a hostile. It inhaled, trying to eat Hiccup as he tried to escape. Hiccup sam to the side, just escaping the gaping maw of the dragon. His pocket of air contraption got caught up in the underwater whirpool and smashed against a rock, cracking the amber slightly. He frantically swam into his contraption, only to find it filling with water. He hurriedly yanked the chain, and nothing happened.
Meanwhile, up on the surface, the Dragon Riders were battling with Viggo. The chain jerked, and nobody noticed, as they were focused on the other ship ctapulting rocks at their ship. Toothless watched the battle anxiously, hoping they would hurry up and get done already. He looked over at the chain worridly, and it jerked again. He barked loudly to get Fishleg's attention and they started pulling it up. Viggo's ship fired another boulder, and this time it hit-right on the chain. The chain fell over the side of the boat and sank.
Toothless dove into the water to try and rescue Hiccup, but the supports had broken on his contraption and he was trapped in a slowly filling with water upside down bowl. Toothless desperately pawed at the glass, trying to get Hiccup out, thinking he was going to lose Hiccup forever. He heard something whooshing behind him and whirled around to see what it was. He saw the Submaripper swimming towards the chain, scoop it up, and dragged the whole conraption to the surface. The dragon dumped it on the Dragon Rider's boat and swam to Viggo's boat, determined to smash it to bits.
Viggo and his brother quickly got onto a small rowboat and rowed away as their boat was smashed beyond recognition. He turned back to see the Submaripper tear the ship in two and the Dragon Riders regrouping at their boat, and then he and his brother sailed behind a cliff, hiding them from sight.
On the other boat, the Dragon Riders landed, only to see Toothless blasting the contraption Hiccup was in.
"NO!" yelled Astrid, rushing forward, trying to see if Hiccup was all right. The contraption now had a smoking hole in both sides where the plasma blast had gone straight through. Strangely, Hiccup was unharmed, and the blast had gone straight through him. But the acid on his back soaked through his shirt and reached his skin, being absorbed by his body. He started to scream, and the smell of burning flesh filled the air.
Toothless realised that his rider was probably going to die, and he walked over sadly to Hiccup and curled around him, tucking his wings around Hiccup.
"Hiccup…" Astrid whispered, rushing over to Toothless and trying to pry open his wings. Fishlegs joined her, muttering all the while about how the plasma blast should have killed Hiccup.
"No no no no NO!" Astrid yelled, her voice rising in terror. Toothless gave a low moan and opened his wings, and Astrid saw, with great horror, what was obviously Changewing acid on his back. To her surprise, the acid was being absorbed, and the more that was absorbed, the less Hiccup screamed. Hiccup finally stopped screaming, and opened his eyes.
"I-OWWWWWW!" He screamed, this time because it felt like his back was ripping. In fact, his back was ripping open in three spots: the shoulder blade, the other shoulder blade, and the tailbone. Toothless tented his wings around Hiccup again and refused to open them. His wings muffled the screaming a little bit, but not all the way. Astrid tried and tried to open Toothless's wings, to no avail.
The screaming finally stopped, and Toothless, without opening his wings, peeked inside to see Hiccup. He recoiled instantly in shock, and then went back in to comfort Hiccup. Hiccup had fallen asleep coiled within Toothless due to the pain. Since Astrid was becoming a nuisance, he grumbled and opened his wings up slightly so they could see his face. Astrid and Fishlegs huddled around him, anxious to see Hiccup. They could see that he was breathing, and therefore alive. He murmured in his sleep, and unconciously curled up into Toothless. He started twitching and clamped his hands around his ears.
Since Toothless wasn't going to move, the Riders picked up the boat and went back to Berk. Snotlout and the twins had endured that in shocked silence, witholding from joking. When they arrived, they were solemn and quiet. When the boat landed on Berk, Toothless bounded off the boat first and, with Hiccup under his wing, ran to the chief's house to let Hiccup sleep in his own bed. Toothless placed Hiccup gently in the bed, and grabbed the blankets in his mouth and pulled them over his sleeping rider.
Toothless heard the door slam open downstairs and Stoic stormed in. He ran up the stairs and flung open Hiccup's door to find Toothless curled up on Hiccup's bed, which broke under Toothless's weight.
"Toothless, I need to see my son. Let me see him, Toothless. I won't hurt him." Stoic said as gently as he could, knowing Toothless wouldn't let him by unless he was gentle. Toothless narrowed his eyes and stepped off the bed. Stoic stepped closer to Hiccup, and saw black… things on the side of his head. He leaned closer, and realised they looked exactly like Night Fury ears.
"What did you do out there?" Stoic asked Astrid, who had just arrived in the room with the other Riders in tow.
"We freed the Submaripper, but… he got Changewing acid on his back, and he somehow absorbed it. H-he was in a lot of pain, and Toothless has barely let us see him since." Astrid shakily replied. She moved forward to see Hiccup, and saw his ears.
"He's waking up." Fishlegs said quietly. Hiccup's eyes were fluttering open. They were regular human eyes, except his pupils weren't round. They were like Toothless's and more oval-like.
"What happened?" Hiccup asked.
Some of you may be a bit confused of why this transformation thing happened, and the answer is that since he was in the water when the acid got on him, it reacted differently. The reason for the Night Fury traits is that Toothless shot that plasma blast, altering the venom impact, so instead of the acid or the plasma blast killing him, they combined to give him Night Fury characteristics. Adios!