Hiccup and the teens have travelled to the future [before he trained dragons]. What situations could this cause? What happens when they find out about what their future holds? The most popular story I have ever written. First chapter is depressing, but the rest shouldn't be.

{Sequel to King of Dragons: Return of the Dragon King.} Frostbite and his friends have time travelled to the past to destroy their archenemy's friend. Too bad they don't know they would meet their parent's past selves and a dark secret that has been kept under lock and key for over a decade. [Better than it sounds. Read the prequel.]