Dota 2 Crossover.
"While Puck seems at first glance a mischievous, childish character, this quality masks an alien personality. The juvenile form of a Faerie Dragon, a creature that lives for eons, Puck spends countless millennia in its childish form. So while it is technically true that Puck is juvenile, it will continue to be so when the cities of the present age have sloughed away into dust. Its motives are therefore inscrutable, and what appears to be play may in fact indicate a darker purpose or just its endless fondness for mischief."

Just so we clear, this fan fiction came first than the Pacific Rim crossover.