Rikku first appears in Final Fantasy X to aid Tidus shortly after he first arrives in Spira. Her Al Bhed comrades wonder whether or not to kill him, but Rikku tells them to bring Tidus with them. He accompanies Rikku on a salvage operation to activate the power source of a sunken airship. After returning to the ship, Tidus tells Rikku that he came from Zanarkand, but she is reluctant to believe him as Zanarkand had been destroyed 1000 years previously. Rikku realizes that he is oblivious about Spira and that he had been affected by Sin's toxin. She promises to take him to Luca hoping he might find someone he knows, but Sin appears and washes Tidus off into the sea.
Rikku is next seen collapsed with exhaustion at a riverbank. Tidus finds her, and is glad to see her alive and well after Sin's attack on her ship. Rikku and the Al Bhed had previously attacked Tidus and the party he has joined. After explaining herself, she becomes the last member to join the summoner Yuna's guardians. After being transported to Sanubia Desert via Sin, Yuna is missing. Rikku suggests going to the Al Bhed base, Home, which is under attack by Guado forces, in hope of finding Yuna there with Rikku's father and Yuna's uncle, Cid. As the guardians make their way through Home, Rikku reveals to Tidus that Yuna's pilgrimage will eventually result in her death, which leads him to suffer an emotional meltdown.
Aboard Cid's airship, they discover that Yuna was at Bevelle, being forced to marry Seymour. The party stops the wedding ceremony, and decide to meet Yuna at Bevelle Temple. Rikku, Wakka, and Tidus are locked in the Via Purifico sewers, but they manage to escape. As the party makes their way to Zanarkand, they meet with the unsent Lady Yunalesca. Yuna refuses the Final Aeon, and the party defeats Sin themselves. After Tidus fades into nothingness, Rikku refuses to say goodbye, assuring Tidus that they would see him again, and is even seen waving at him as he jumps of the deck of Cid's airship.
Two years later, Rikku, now age 17, joins the Gullwings, a band of sphere hunters led by Brother. The only character from Final Fantasy X other than Yuna to be playable in Final Fantasy X-2, Rikku remains steadfastly loyal to Yuna, giving her support when she discusses her feelings concerning the loss of Tidus, and her hopes to find him once more. In the two years that passed between the two games, Rikku managed to overcome her astraphobia – by camping out on the Thunder Plains for a week.She also has a tendency to use odd expressions such as "disasteriffic" and "oh, poopie!" – expressions Yuna would sometimes pick up on (whether Rikku knew it or not, Yuna was now regarding her as something of a role model). She is the only main character in the game with no significant plot role.
Since the conclusion of Final Fantasy X, Brother and Rikku had a falling out with Cid. When the Gullwings look for a sphere among the Zanarkand ruins, they find that Cid and ex-summoner Isaaru had turned the once sacred place into a tourist attraction, which comes as a shock to Yuna and Rikku. When Cid asks whether they have a bone to pick and Yuna replies "You bet I do," Rikku tells him it's just like turning the ruins of Home into a theme park, causing him to retreat to the Thunder Plains to sulk.
Rikku meets up with her old friend Gippal – now the leader of the Al Bhed Machine Faction – who, being quite the ladies' man, would tease Rikku with his flirtatious jokes, including one about them having "made quite the couple" – though it was unclear whether he was referring to romance, given his nature. Also, as Paine kept quiet about her past – and also that Gippal jumped a mile when he saw her, as well as the other faction leaders seeming to know her – Rikku would sometimes prod and poke her about it, only to succeed in annoying her. However, in their journey, Paine eventually tells them about her role as a sphere recorder for Crimson Squad, alongside Gippal, Baralai, and Nooj.
Upon meeting her young friend Calli on the Mi'ihen Highroad, Rikku and the Gullwings decide to help her catch a Chocobo. Later, during the Mi'ihen Highroad investigation sidequest, Rikku is one of the suspects when some machina malfunctioned after the Gullwings did this. If clues are arranged in a specific manner, Rikku is named the culprit and assigned clean-up service to make up for it.
In Final Fantasy X-2 International Last Mission, Yuna, Rikku and Paine reunited after being disbanded three months after the game ended. While exploring the Yadonoki Tower, it was later found out that Rikku spends her time searching for sunken machina on the ocean floor. She shows a bit of annoyance to Yuna and Paine, but it was because she felt she was cut off from them, and reluctant to consider that they may have lost their friendship in the times (Yuna living with Tidus, Lulu and Wakka in Besaid, and Paine traveling independently). After realizing that they all share that sentiment, all three girls promised each other that they will write and keep in touch, ensuring that their friendship will never go away.
Despite the fact she spends the majority of Final Fantasy X-2 wearing a bikini as part of her attire, in the one story-sequence in the game that requires the character to wear a swimsuit she dons a different one-piece suit.
Age: 15 (FFX), 17 (FFX-2)
Height: 158 cm
Eyes: Green with swirl around pupil
Tribe: Al Bhed
Languages: Al Bhed, English
Family: Cid (father), Brother (brother), Yuna (cousin)
Fears: Thunder (only in FFX), the Farplane
Battle Role: Thief
FFX Weapon: Claw
FFX-2 Weapon: Twin Daggers
FFX Official U.S. Profile: Rikku is a young Al Bhed girl. Her personality is upbeat and positive, and she is not afraid to speak her mind. She works hard to restore her outcast people to their former glory. Rikku handles mechanical enemies with ease, and can steal items from enemies, too.
FFX-2 Official U.S. Profile: In the two years since she helped Yuna defeat Sin, Rikku has travelled with other Al Bhed around Spira, teaching people all there is to know about machina. During the so-called "search for truth" that overtook Spira after Sin's defeat, a group of Al Bhed joined the ranks of sphere hunters. With their airship the Celsius as a base, Rikku and her Brother founded the Gullwings. Rikku invited Yuna to join the Gullwings, and they have been traveling together ever since. As always, Rikku's endless supply of energy keeps the team on their toes.