About the AUEdit
Spawning from fanart, this AU places the Big Four, and other such characters in the fandom, are people playing with their friends/toys (like Bolt's Mr. Carrot, Hiccup's toy dragon and Hiro's Megabot) in the 100 Acre Wood or portrayed as characters from Winnie the Pooh.
The Big FourEdit
Fans have portrayed Riley as a female Christopher Robin, with Joy, Bing Bong and the other emotions as Pooh and their other animal(-toy) friends. Joy as Pooh Bear or Tigger, Sadness as Eeyore, Disgust as Owl or Rabbit, Fear as Piglet, Bing Bong as Tigger or Lumpy and Anger as Gopher or Rabbit.
Hiro is cast between Christopher Robin, when Baymax is Pooh and Winnie the Pooh, when Tadashi is Christopher Robin. Hiro can even play in the woods with Baymax, Megabot and the other toy robots that sit on his shelf.
Since Cassandra's Owl is a bird call "Owl", he can easily be portrayed as Owl from A. A. Milne's Winnie the Pooh.