About this AUEdit
The Big FourEdit
Hiccup and the rest of Berk can be Orcs, since they're a proud warrior race, they have to fight and conquer to survive (much like real Vikings), and Orcs can grow serious beards and hair braids in addition. Since a few Orcs have lost limbs in battle (Kargath Bladefist), prosthetics such as Gobber's interchangeable hands wouldn't be too out of place. Hiccup would probably be an outcast (not to be confused with the Outcast Tribe) due to his physically weak nature, similar to Thrall's own mother Draka at his age.
Jack would be an Night Elf, due to his white hair (a few Night Elves had white hair, including Queen Azshara), his connections to nature, and his ability to perform magic with a staff and can fly. It helps that Jack is officially described as an Ice Elf by the writers of Rise of the Guardians.
Merida would be a Tauren, due to her kingdom being a clan-based society, deeply in touch with the earth (like the Ring of Stones), and being united to fight a bestial enemy (the Centaurs as opposed to Mor'du). Since most Tauren are peaceful but will gladly fight to protect themselves, Merida's impulsive hands-on attitude would strain her family relationships. Merida is also seen being apart of the Dwarven race.
Rapunzel would be a magic human, perhaps born to the kingdom of Dalaran (as Rapunzel's father is a brown-haired king like Varian), and potentially in training to become the next Guardian. Her friend, Pascal, would be a baby Kodo.
Elsa would be a Dwarven of Ironforge, due to her living in a kingdom that is next to a snowy mountain, wears her hair braided and is duty-bound to serve as queen, much like Magni. Of course, it would mean having to make Elsa a lot shorter. Elsa is also seen being apart of the Northrend world, while her ice magic can make her a Mage. Fans have also portrayed her as Sylvanas and a female Arthas.
Anna would be a Dwarven of Ironforge, due to her living in a kingdom that is next to a snowy mountain. Her hair braided gives Anna a desire for adventure like Brann Bronzebeard. Of course, it would mean having to make her a lot shorter. She is also seen as a Dwarf for being stubborn, lively and tougher than she seemed.
Moana and her people would be Worgen. They live on an isolated island due to Chief Tui's law that forbids them from going beyond the reef/wall, and their island fallen prey to a darkness/curse. Moana's struggle lies in not only balancing her love for her people and her love for the sea, but in maintaining her humanity against her bestial side.
The Guardians would be demigods chosen to protect the realm of Azeroth from the Burning Legion. Their species would be determined by where they live, North would be a Dwarf demigod, due to his beard, his warrior spirit, his inventive nature and his choice to live in the freezing north of Azeroth. Sandy would be an demigod resembling a Golden Dragon, due to the fact that the dream weaver in Warcraft is also a Dragon, Ysera. Toothiana would be a Night Elf demigod like Cenarius, but she'd be half-owl (or hummingbird) instead of half-deer. Bunny would also be a demigod of the Night Elves, due to his role as a nature protector, but because he's the only completely animalistic Guardian, he'd be one of the Ancients, like Goldrinn or Agamaggan.
Toothless and the rest of the dragons can be from the Dragonflights. Giving them the ability to become humanoids and embody the powers and attributes of their respective coloured Flights. Hookfang, a Red Dragon, can breathe cleansing fire, and prizes life. Barf and Belch, a Green Dragon that can control dreams. Meatlug, a Bronze Dragon that can watche over the passage of time. Stormfly, a Blue Dragon that can presides over the study of magic; and Toothless, a Black Dragon that watches over the earth. As a Black Dragon, Toothless would receive the most negative press from the Berk Orcs, since he's one of the children of Deathwing the Destroyer, and would have to work really hard to make friends with the Vikings.
Flynn Rider/Eugene Fitzherbert is a runaway robber perhaps orphaned during the fall of Stormwind, who passed near Dalaran on his robbing escapades and came across Rapunzel in her tower.
Te Fiti is a relation of Therazane the Stonemother, one of the Elemental Lords, and one of the main deities worshipped by Moana's village as a tribe of Worgens.
Hans is seen as Terrible Beast that won't stop for nothing to get what he wants, with no remorse and only determination. Much like how he had tried to win Anna's heart and to kill Elsa so he could be come the King of Arendelle.