Fionna is calm, she can be provoked to anger. She will often try to act like one of the guys, so she fits in easily with friends like Marshall Lee or Prince Gumball.
Fionna is a fearless, thrill-seeking, adventure-loving hero who will rescue any prince from the Ice Queen or do any task to better herself or help citizens. She, much like Finn, is also very hard-headed as shown when Cake wanted her to date Prince Gumball and she was stubborn about it.