Not much of her character is explored, but it's implied she may be vain and is very sensitive. This vanity was shown when Dr. Blip tried to ask her out to dinner, but she harshly rebuffed him for ‘being a weakling,’ although she later kissed him after he saved her life. In Target: April O'Neil, she left the team because the team forget her birthday. It's unknown what else has caused her to leave, but it's likely her vanity and sensitivity are part of her constant leavings. However, she also seems to be kind-hearted and peppy, as she constantly cheered on her team. She is apparently the cheerleader of the group.
In one episode, Leonardo mentions that the princess has left the team more than "twenty times" and always returns, to which Michelangelo has indicated that the show "paradoxes" Donnie's life (although he meant "parallels").