The dragon: Natalie wanted it to have a serpentine feel and felt that it should have a pattern on its forehead that hints towards a second pair of eyes, which is considered to be a scary element of monsters/creatures.
She also wanted the dragon to be able to be cute at the end of the films so she has made the dragons eyes bigger and softer with the pupils round and large rather than the slits it has at the start.
The Knight: Natalie has pushed the shapes of the knight further to make him more cartoony and funny.
The Damsel: She wanted the damsel to have an alternative feel and unique design. She didn't want the normal skinny big chested character so looked for alternative options. she decided on a more curvaceous character, who is a strong and beautiful.