Very interesting start. I've always enjoyed the complexity of Norse Mythology. Nice to see a fic incorporating that into the plot. I hope to see more of this soon.

Well. You know exactly how to setup an epic. I loved your representation of Hiccup the II, and your narration was brilliant. I can't wait to see where this is going.

This is good, but confusing as hell. Jumps around and you never really understand what's going on and then it kinda clicks, then there's another page break just as you're understanding that confuses you once more. It would be a bit easier if it all took place in chronological order. Not the first rag, jump to second, then back to fist, hi hiccup! Wrong hiccup type deal. Otherwise, I think you have a hell of an idea.

We'll yay story

But fucking Loki

A bit preachy and the exposition dragged at times, but it is very well written. It is clear you put a lot of effort into crafting a story of interwoven plots and characters and these themes, at least for the prologue, have been well thought out. I liked how you amplified the best personality traits of HHH3 and created an aged parallel of his personality with HHH2. It is really similar to the book series representation, with themes of their interconnection via both dragons and their capability to reshape fate, so I imagine you must at least be moderately aware of Cressida Cowell's charming-but-ridiculous works. If you continue this, great. You have strong writing skills and I would read more. But given the complexities of your plot, I am guessing this is a doomed endeavor from the start if you are no longer inspired by the fandom. Do whatever feels right.

It's a very promising start. I like the multiple split perspectives and the massive scale that is hinted at (combining HTTYD 1 & 2 as well as Norse myth); I think it really whets the appetite. I'm particularly excited for the Hiccup II portions and his hinted at friendship with a dragon.

Now I'll admit that Hitchups was not really my cup of tea, though its quality and influence in the fandom is undeniable. It clearly influences your story as well, but it convincingly establishes itself as an original universe with vast potential. Best of luck for this story! I'll be watching.