Well I’m sure you triggered some people with this

And we moved into hybrid zone.
Leaving the story here. It was a good story so far. You could've warned in the story description.
You're a good writer. Sorry but hybrid Hiccup isn't my cup of tea.

I'm pretty sure Storm cutters can't breathe fire.

the story was good. had a few spelling errors but that is to be expected and is an easy fix. you wrote a good story. are you planning a sequel?

is it weird that I'm so obsessed with HTTYD, that I can quote pretty much every sentence said in the movies and some episodes of RTTE and TV series?

Satan? They're VIKINGS! Norse tradition, not Jewish nor Christian!

Get characters their own lines!

This is the most fucked up story I ever read. I see what you are trying to do but it's not working. The scene "You are as beautiful as the day I lost you" it doesn't fit in this. It just doesn't. The words it's self just state the feeling of calm, hope and mind peace. It's totally opposite to the scene where it was a fight, death. Everything is so rushed. If you would consider the story as it would happen in real time you would see you need to give time for certain things. I'm sorry but I'm not your fan.

Its really the end?

I REALLY WANT A NOTHER STORY ABOUT WHAT IF HICCUP AND HIS MOTHER WAS TAKEN BY DRAGONS SIMILAR TO THIS ONE

Wait, what happened to the night fury's on Outcast Island? Did Val get a chance to free them 1st?

I was a bit confused how they didn't figure out how Eret knew Hiccup's name or why Hiccup told him he didn't trust him and then just fell asleep...

I love the idea of Hiccup being raised by dragons and his Mother instead of the tribe. I would love to see more of that. :-) I also love it how Hiccup does not like his father at all and won't tell him his name so he doesn't know he's alive. I would also really want to see hiccups father trying to figure out who the Dragon riders are more. But I don't really see Astrid being the blacksmiths apprentice in the tribe I think fishlegs would fit that role better. I would also love if there was more of hiccup and his mother sneaking around and no one knowing who they are especially the father. I just feel like hiccup excepted the father to quickly and the father not really earning it. I also think that making hiccup turn into a dragon didn't really fit in this story. You got the character personality perfect.
I think this fanfiction is really good and I would love to see more of a fanfiction similar to this one pretty please :-) thank you for it :-)

Not sure I like that Astrid is basically just standing in for Hiccup here. Also, her inventing and building a bola launcher out of boredom is ridiculous. Hiccup only even built that thing because he couldn't "even throw one of these" on his own. It probably would've been better if you just had her throw the bola herself really hard if you're that insistent on having her fill Hiccup's role here.

Nightmares don't use gas. Their fire breath is more like molten rock.

NEVER put author's notes in the middle of the chapter. They should only be placed at the beginning or end. You can leave a superscript number after it and put the note down at the bottom if you feel you really need one, but you should never break the story's flow with a note in the middle. That particular note wasn't even necessary anyway.

Second author's note in the middle of the story. If you really wanted to explain that, have Astrid ask him about it later so he can explain it to her and us at the same time, though I think most readers could figure out why he knew both languages.

Hiccup is in no position to ask questions; Astrid's the one with the ax.

Saying "jaw hit the floor" is a really lame phrase if you use it more than once in a row. Astrid also has no reason to believe what he's telling her, especially since he and his mother are believed to be dead.

How is Toothless still trapped? Hiccup just got out of the net.

What the hell does she mean "What are you going to do with that?"?! He pulled out a weapon and is clearly a sympathizer with what she believes is the enemy! Even if she didn't think he was going to attack her, she should at least know that Hiccup's going to set his dragon free.

He has a flaming sword, is clearly one of her enemies, and her first comment is that he would make a better blacksmith apprentice?

Unnecessary capslock.

"Well neither am I" (sic) did make sense.

Yeah, bringing back the heir only to show he's one of their enemies will bring her a load of social status.

How does Hiccup know where his dad lives or where Astrid was or where she was going? Why is he still around after she took a nap and had breakfast? How does he know his dad's name? Why isn't his mother with him? It just raises too many questions.

There's no way she'd be comfortable enough around him to tease the way he sounds.

He either asked or threatened. Pick one.

Your characters are too easily shocked.

HOW would anyone other than Valka and maybe Hiccup know that she was about to kill Cloudjumper?

Hiccup said "gonna". Boo.

Hiccup could have just freed himself and Toothless right away or killed Astrid on the spot, so he did have a choice.

Clunky expo-speak from Hiccup.

There's nothing stopping Astrid from telling Stoick at this point now. None of her previous reasons for doing it have changed.

Nobody else sees or hears Toothless or Hiccup or Astrid yelling at each other?

Wow