Dawn of the Dragon Guardian

"Not every person knows the truth, some rulers made sure to hide every fragment of the past"

After Hiccup retrieved the Dragon Eye from Dagur, something in him told him to keep the mysterious object a secret from the rest of the dragon riders, it wasn't until the rest of them were busy with their own busy schedule, each of them finding their own vocation and giving up finding more new species of dragons, he decided to explore what the object was made for, thanks to dragon fire light, they found the different islands that it was shown, Heart Break Island it said in the light. His journey would start there.
Without knowing, his path would be threading softly, ancestors of his past will be uncovered, discovering the truth behind the years of conflict and wars between dragonkind and humankind. Would Hiccup want to go back to Berk after everything he learned and seen, the secret island of dragons, the truth about Berk, but the most important part is: upon arriving, he feels like home in Dagsátr Island, would he give up his only chance on freedom and exploring dragons or would he go back to his tribe to take one day the role of Chief and feel himself getting lost in his own tribe.

Or a, "what if...?", where Hiccup in RTTE goes to retrieve the treasure Johan left behind, encountering Dagur, and stealing back the Dragon Eye from him, he goes on an adventure to an island where he will discover the secret of his past ancestors.