hybrid hiccup

This hiccup, he used to be a human until a Night Fury slashed his belly. He was unconscious, but the other person found him and he woke up. At nighttime, the full moon rose. He slowly transforms his tail, grows his skin into black scales, and he grows much larger, taller, and muscular, becoming a hybrid nightfury, so he fled away from berk so he will be the rest of his life a muscular nightfury there where you come in