Well, the answer for Cressida Cowell it seems is to just get right back into the saddle and build a whole new world with new characters that's just as enchanting, dark, mysterious and magical as that aforementioned well loved series.
Cressida Cowell has dazzled us in the past, not just with her fabulous chronicles of Hiccup Horrendous Haddock III but with awesome creations like Emily Brown too. We expected great things of her new book - and we definitely weren't disappointed.
"The Wizards of Once" is Cressida's new series, and although you won't get your grubby mitts on it until the 19th of September 2017, we couldn't wait to dive into our advanced preview copy to try and get the inside track on Cressida's new creations.
This time round you've got not one but two characters to fall in love with (and trust us, you will find a favourite very quickly. Xar is a young wizard boy, a bit rough around the edges but with a thirst for magical knowledge that will see him stopping at nothing in order to gain mystical powers.
Wish is a warrior girl with strengths beyond her years. A strange magical artefact falls into her possession and before long it's a life-struggle just to keep the strange object concealed and away from prying avaricious eyes.
The two soon make a very odd alliance, with neither really quite fully trusting the other, but both with a perilous quest to undertake - to return the strange object to Warrior Fort.
Cressida instantly sets up a breathtaking fantasy world where magic and warrior factions are constantly at loggerheads, putting our two heroes in an unenviable position from the get-go. Underpinning this thrill ride are dark forces and a mysterious entity that has slept for hundreds of years, and may now awaken once again, putting the world in peril.
Instantly we were both struck by how much more dark, more 'grown up' and yet utterly and completely compelling this story was, so there's a tiny bit of concern that fans of HTTYD might be all at sea to begin with. But as the story comes to a close, and leaves you absolutely gasping for more, those fears are soon erased.
If major studios have any sense, they'll be gnawing Cressida's hands off for the movie rights to this, because come September, "The Wizards of Once" looks set to do for Middle Grade fantasy what "Game of Thrones" did for the grown-up stuff.
"The Wizards of Once" by Cressida Cowell is out on September the 19th 2017, published by Hodder Children's Books. Get it on your preorder list now!