The characters are trained to be sensitive to frightened little ones. We had the same experience with Cruella. She was the only character my then-6yo DD would NOT go up to. (I think most of the scarier characters are in heads, which makes them unrealistic. Cruella is a face character, which hit a little too close to reality.)
My then-23mo was frightened of ALL of the characters at the beginning of our last trip, and just started warming up at the end. The first ones she would go near at all were Cinderella's mice. They played Ring-A-Round-A-Rosie with her. They were smaller than the other characters, and very cute and unintimidating. (We found them with Cindy at the Meet and Greet near Mickey's tent in ToonTown.)