Fiel Nirvalen, who usually has her name shortened to Fii, is an elf girl who is Chlammy Zell's game partner, as well as the one who helps her cheat using her elven magic. Despite her young physical appearance, she is actually around 52 years old.
It is subsequently revealed that Chlammy is actually her family's slave. Despite this, they hold a close relationship between each other. She even begs Sora to restore Chlammy's memories after the latter won them in a game. Believing that Sora's going to fulfill his words to unite all races, she now works with Chlammy to claim the leadership of Elves as she cares more about Chlammy than her own race.
Fiel has long golden hair with a pink ribbon that keeps a portion of her hair in a plait and eyes with dark blue irises and pink clover-like pupils. She has a rather large bust. Her outfit has an olive green and pale yellow creme color scheme.
She greatly cares for Chlammy, even risking her life for her during the Reversi game. Despite having pride as an elf, she is willing to swallow it for the sake of Chlammy. While usually smiling and with a soft voice, she can get serious when the situation calls for it. She also harbors a slight hatred for Flügels, particularly Jibril, as they killed a great number of elves in the past.
She seems to be sensitive about her age, as shown in the anime.
She is a hex caster (able to cast and maintain up to six spells at once), a very rare capability that only an extraordinary few possess. However, to protect and aid Chlammy, she hid her magical prowess from the rest of the elves, resulting in them believing Fiel to be a poor magician and a disgrace to the Nirvalen name.
She is also a very smart person. As stated by Sora, Fiel was able to grasp Sora's true intentions without the use of magic.
She is very protective of Chlammy and would go to great lengths to keep her safe. This could prove to be a possible extortion factor if Chlammy was ever to be threatened or taken hostage.
She shares her voice actress with Tiffania Westwood from Zero no Tsukaima. Another similarity between the two is that they are both elves.