Harry Potter and the Dragon Tamer

Hiccup and his fellow Guardians are called to Hogwarts to help with the TriWizard Tournament. When they get there, they're allowed to attend classes, but they refuse to be sorted. While they're there, they learn where five dragons that had gone missing are there for the tournament. HiJack, Toothbite, and other pairings. Hogwarts AU. ROTBTD.