Hela Horrendous Haddock was the strange daughter of the Chief of Hairy Hooligan Tribe and had the misfortune of being the most un-Viking-like Viking to be born on Berk. Small, weak, and clumsy, Hela doesn't fit in with what the tribe thinks a future Chief should be.
During one of many dragon attacks, Hela, determined to prove herself to her father, manages to sneak out and shoot down a dragon. However, due to the many, many, many instances in the past, no one believes her. Left to her own devices, she goes searching for it and finds herself unable to kill it, leading her down the most un-Viking-like path a Viking had ever walked before.
Or,
How To Train Your Dragon but Hiccup is Hela, Astrid is Aron, Toothless is adorable, and Stoick is just trying to connect to his daughter while running a village.