Long ago, the goddess Hylia created Fi to guide the chosen hero to stop Demise should he rise again.
After Link loses Zelda to a rogue tornado, Link follows Fi to the Goddess Statue where Fi reveals a secret entrance below. She explains to Link that she is here to guide him in his destiny as she points to sword in pedestal. Throughout Link's adventures, she guides him to his objectives in locating Zelda. When Link finds Zelda in Lanayru Desert, Zelda and Impa escape from Ghirahim though a gate in time. Afterwards, Fi and Link soar to the Isle of Songs where Fi accompanies Link who completes the three trials in the areas he has recently explored. In these three trials, Link searches for the sacred flames to bath both the Goddess Sword and Fi in order to upgrade the sword to the Master Sword.
After forging the Master Sword, Link and Fi returns to Thunderhead where they exterminate a parasite on Levias. Receiving Levia's request, Link and Fi venture forth to explore the lands again to search for the parts of the songs from the dragons. Fi has remained by Link's side until Link crashes in Eldin during the volcanic eruption. Link eventually claims back Fi. With the Song of the Hero completed, Link and Fi soar to Skyloft to complete the last Silent Realm trial. After the task has been completed, Fi assists Link in obtaining the Triforce. Despite that the Triforce has sealed Imprisoned, Fi and Link have to rescue Zelda from Ghiraham who unleashes Demise.
Upon defeating Demise, Fi bids Link farewell due to completing her task. She thanks Link for the precious memories from their adventures. Link sets the Master Sword back in the pedestal where Fi enters an eternal sleep.
Fi is emotionless, calculative being. She makes predictions and gives advice to Link. As she spends time with Link in his adventures, she opens up. At first, Fi only thinks Link as her master. Now, she views Link as a friend, and she cherish the moments between Link and his friends when she mentions that she has recorded them. She expresses that she is happy. Fi thanks Link for giving her those moments.
Despite being a robotic being, she has a passion for dancing and singing.
Fi is a small, female humanoid who has legs but no hands. Her face is completely blue. She has a diamond embedded on her forehead, and she has no pupils. Her cape is divided into two sections: left is light blue while right is purple. She has a blue diamond shaped gem on her chest. Her legs have a light green diamond shaped pattern.
I lack sufficient data to be sure of my conclusion, but I believe this feeling correlates closest to what your people call...happiness.
Our partnership is at an end, and even as we speak, I feel my consciousness fading away.
Many have said them to you thus far, but I now wish to say them for myself... Thank you, Master Link. May we meet again in another life..
— Fi's Final Words
- Link - Because of Link's adventures, Fi's role from being master and servant transforms into friendship (from Fi's perspective). In her final moments, Fi expresses that she is happy and thankful. In one of the side quests, Fi warns Link about pursuing a relationship with Peatrice (during Fi's analysis).
- Fi acts as Link's translator in a Hyrulian language.
- She serves as Link's dowsing rod in finding Goddess Cubes and all sorts of things.
- Fi's telepathic abilities enables her to call Scrapper, a robot that is in love with her.
- Fi is able to record data such as songs and messages.
- Fi's intelligence grants her analytical ability where she searches for the enemy's weak spots to aid Link.
- Fi's name in Japanese is ファイ Fai.
- Like Midna, Fi speaks gibberish.
- In an interview with Eiji Aonuma, he states that Fi has no gender. Yet, he acknowledges that Fi has a feminine figure.
- Fi's color scheme is similiar to the Master Sword.
- Fi is the female counterpart to Ghirahim since both of them can form into swords. Ghirahim's final form is quite similar to Fi's appearance. Both of them have the same hair style and gem shape that is embedded on the chest. While Fi is emotionless and calculative, Ghirahim is very emotional.