Mark Mayerson has posted a terrific analysis on his blog of the different ways that sympathy can be created for animated characters. He uses plenty of examples from Disney films. Mark writes:
Sympathy turns out to be a major factor in whether or not an audience roots for a character and based on animation history, the character can be passive or active. I can think of only three ways to make a character sympathetic. If a character obviously does not have the ability to protect himself or herself, if the character is treated unfairly for any reason, or if the character is attempting to help another, more needy, character. A character who is defenseless, the victim of injustice or altruistic will automatically gain audience sympathy.