Last updated: 17th July 2013
When they first meet: Rikku joins Tidus during a battle in the Ruins at the start of FFX. He doesn't know who this girl is and he doesn't understand her Al Bhed language either. Rikku's group thinks that Tidus is a fiend in disguise and wants to kill him. Rikku stops them and says in Al Bhed "Wait! What if it is human?". She then knocks him out and they take him to their Salvage Ship. Here Rikku speaks to Tidus in Spiran and they can finally communicate!
Tidus and Rikku easily bond. Their friendship is kind of like a brother-and-sister-relationship. They also have similar personalities which is awesome.
Depending on how many affection points (affection mechanics is a hidden feature in FFX) the player has accomplished to get between Tidus and Rikku, they may end up like this in Guadosalam:
When they first meet: They know each other from before, but we first see them together in Moonflow after the underwater fight with the Machina. Rikku tries several times to disrupt Yuna's Pilgrimage because she knows what will happen if Yuna succeeds... Rikku becomes Yuna's guardian.
Rikku is Yuna's younger cousin (Rikku's dad's sister is Yuna's mother) and she looks up to her. Rikku likes to call her "Yunie". In FFX-2, Yuna sometimes uses Rikku's phrases such as "disasterrific" and "oh, poopie!".
When they first meet: They first meet in Moonflow after the underwater fight with the Machina. Yuna wants Rikku to be one of her guardians and asks Auron for his permission. Auron tells Rikku to show him her face (eyes, really!). Auron thinks it's okay if Yuna wishes it. Great!
It seems that Auron thinks Rikku is a bit of an annoying girl. Especially in Thunder Plains; Rikku is scared of lightning (like really scared), and she wants to go rest at the inn. After pleading for a while, Auron says: "Fine, we rest. She's worse than the storm". After resting for a bit, they all want to go on, except Rikku. Auron says: "Fine. Stay here", and walks out of the inn. But in another scenario in Macalania Temple Auron comes to her defence; the guard doesn't want to let an Al Bhed enter the temple. Rikku says "I've decided to be Yuna's guardian now, and that's all I want", and Auron follows up with "And that's all one needs to be a guardian". Awwwh.
When they first meet: They first meet in Moonflow after the underwater fight with the Machina. Wakka really dislikes the Al Bhed and the use of Machina, but he doesn't realize that Rikku is one of them before later in the game (the others kind of keep it a secret from Wakka). At Lake Macalania the group fights another machina (piloted by Rikku's brother, Brother). He speaks Al Bhed and Rikku replies to him in the same language. Wakka wants to know why Rikku can speak Al Bhed. He gets upset and they have a small argue. Later at Home, Rikku tells him about the Al Bhed and how they used to live and he begins to understand why they do the stuff they do, etc.
Rikku kind of changes the way Wakka sees things, like the Al Bhed and machina. That is great! Instead of just believing in the Teachings of Yevon, he manages to see things from different viewpoints.
When they first meet: They first meet in Moonflow after the underwater fight with the Machina. Lulu doesn't say much about Rikku, but she accepts Rikku to be Yuna's guardian. Rikku looks up to Lulu and says she wants to be more like her.
At the Thunder Plains Lulu advices Rikku to learn some spells to overcome her fear of lightning. This could be a reference to the Sphere Grid, since Rikku's grid crosses over to Lulu's.
When they first meet: They first meet in Moonflow after the underwater fight with the Machina. Rikku and Kimahri doesn't have much in common or talk much together at all. But when Rikku tells Tidus that she wants to be more like Lulu, Kimahri says: "Kimahri think Rikku should stay Rikku". How sweet!
When they first meet: Guadosalam. More coming soon.
When they first meet: This man is Rikku's father. More coming soon.
When they first meet: Brother is Rikku's brother (..duh). More coming soon.