Oswald was Walt Disney's very first cartoon icon premiering in several cartoon shorts for all to enjoy. However, due to copyright issues, Disney lost the rights to Oswald and was therefore forgotten and left in the dark. It wasn't until a sorcerer named Yen Sid came to save him and created a new home for him and the other forgotten toons called "Wasteland." However, before he started to settle in as the new ruler, Oswald discovered that another cartoon named Mickey Mouse took his place and became jealous of his new rival. Despite that, Oswald swore that he would do whatever it takes to protect his fellow forgotten toons, including his wife, Ortensia Cat.

The original voice actor in Epic Mickey, Frank Welker, used a "kiddy" voice to make the character sound more like a young teenager. I would encourage you guys to give that same impression or just come up with your own interpretation suitable for the young rabbit.