The Triwizard Tournament was a magical contest held between the three largest wizarding schools of Europe: Hogwarts School of Witchcraft and Wizardry, Durmstrang Institute, and Beauxbatons Academy of Magic, each school being represented by one Champion. Selected Champions compete in three tasks — traditionally judged by the Headmasters or Headmistresses of the competing schools — designed to test magical ability, intelligence and courage.
I really think that 'til 2014 Zayn and Harry were friends. I believe they're both ambitious and the most successful in their solo careers. Probably there was always a bit of competition between them, but it didn't have to be bad, could be healthy. I think other stuff happened, and that's why their friendship is dead nowadays. Maybe Zayn was a bit dick with the other boys in the last year... it was his way of scream: HELP! But he was ill. Harry wasn't very understanding. Things are complicated.