Feefee is very quiet and considerate, and does not really get offended much. Ruby describes her as having a kind and gentle soul, as she forgave her trainer even after he was harsh towards her.
Despite her quiet demeanor, much like Ash's Snivy from the anime, she will put her life on the line to rescue her friends.
When praised, she often smiles.
Feefee cares greatly for Ruby and takes what he says to heart.
After Ruby's escape pod gets tangled up in a Swimmer's fishing line, he was forced to repay him by helping him find the very sought after Fish Pokémon. And since the swimmer never specified it to Ruby, Ruby thinks that the Feebas he caught in the hook was not the Pokémon the swimmer was looking for, thus releasing it into the water. After a while, it gets hooked again and again until Ruby gets annoyed at how it kept coming back, this surprises the swimmer which makes Ruby's PokéNav fall into the water, after interrupting the feud between a wild Zangoose and Seviper, Feebas protected them by using Light Screen and returns Ruby's PokéNav afterwards, much to his disgust. Although the swimmer did not allow the Feebas to not be taken in by Ruby since it has taken a shine to him, Ruby was forced to bring it with him on his journey (thus naming it Mimi) which he plans to set free later. A few chapters later, he ends up fighting with Mimi which made it leave, making Ruby really depressed, crying himself unconscious. Mimi later comes back to him during his battle with Team Magma and Team Aqua, evolving into a Milotic. It later wins the blue ribbon.
Fee fee fights Emerald's Sceptile, using her ability to nullify all of her foes attacks, and lands a Blizzard on Sceptile and freezing it. Unfortunately, she was still defeated by her opponent after it regained its memories, giving it the willpower to break free of the ice.
Feefee briefly fought Amber's Gorebyss.
- In the Chuang Yi translation, Feefee was known as Mimi.