Fionna

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

During the events of "The Prince Who Wanted Everything," Fionna shows a rather ignorant personality towards Lumpy Space Prince. However, this trait may only exist in Lumpy Space Princess's stories, as LSP herself has a very similar personality.

When her reality lost magic, Fionna lost all her memories of her adventurous life, becoming an ordinary human. She expressed great discontent in the world she now lived in, seeing it as boring and desiring something more. This resulted in her becoming jaded and depressed over this period of time. She had many jobs but hated every single one of them, often getting herself fired. The only time Fionna ever expressed any sort of enjoyment in her non-magic reality was when she was with her friends, though that may have only been to save face with them as she still felt sadness on the inside, something she didn't always hide when she was around them. Fionna appears to also have developed quite a taste for sugar, as stated by herself she has “no impulse control”.

Upon landing in the Land of Ooo, she was excited to be in a world of magic and yearned to explore. Despite losing her memories of her previous life, Fionna still retains her love for adventure, finding it to be natural. She also has a strong attachment to having freewill, as she heavily disliked the idea of having to return to her reality while it still lacked magic. After seeing what her world was previously like, she was excited and wished to reclaim such wonder by traveling on an adventure. It is shown during her interactions with Simon that Fionna is a romantic at heart, and seems genuinely enthralled by his retelling of how he and Betty met and fell in love.

As housemates, adopted sisters, and best friends, Fionna and Cake share a very deep and strong bond. Having been raised together by Cake's parents, the duo share a relationship similar to that of siblings, with Cake watching over Fionna and giving her advice constantly as her older sister. Though they have an unconditional love for each other, Fionna can get frustrated with Cake because of her pushiness, shown especially in "Fionna and Cake." Though she sometimes leads Fionna down the wrong path, Cake genuinely means well for her companion and is usually an encouraging and protecting figure. It is shown in the Card Wars comics that the two would go to great lengths for each other, despite the fact that Cake initially ignored Fionna (to train for the Card Wars tournament- similar to her counterpart, Jake.) to study for the competition.