Depiction in the series
In Sweet and Elite, Rarity states she was born in Ponyville. During The Cutie Mark Chronicles, Rarity retells her story of her life as a filly to the Cutie Mark Crusaders. The flashback starts on an outdoor theater near the Ponyville Schoolhouse, where some fillies are practicing for a school play, dressed as various foods. The teacher compliments Rarity on her costume design, but the perfectionist Rarity insists that the dresses don't meet her expectations and tries to create new ones to no avail. Almost immediately, a light ignites in her horn, and it drags Rarity leftward until it stumbles into a very large, geode-like boulder. Rarity, having thought her horn would help her find "[her] destiny", is deeply unsatisfied. Then, Rainbow Dash's sonic rainboom occurs, causing the boulder to split in two, revealing it to be filled with gemstones. Rarity decides to add these to the existing costumes to jazz them up, earning both the admiration of the crowd and her cutie mark. Rarity is responsible for the decor during the Summer Sun Celebration. When she sees what Rainbow Dash accidentally did to Twilight's hair, she is compelled to give the latter a makeover. She also develops a fascination with Twilight when she hears she is from Canterlot. Twilight flees the Carousel Boutique in fear of the thought of Rarity dying her coat a new color.
Rarity daydreams in The Ticket Master about meeting Princess Celestia's dashing "nephew" at the Grand Galloping Gala, with her fantasy culminating in marriage and induction into royalty. Upon attending the Gala in The Best Night Ever, she spots a stallion, depicted with the same character design as the one in her fantasy, who is identified as Prince Blueblood. Although handsome and initially charming, Blueblood turns out to be conceited, rude, and narrow-minded. He expects Rarity to care for him while doing nothing in return. Rarity tries to be patient with the prince's manner, but his selfish ways finally exhaust her patience when Blueblood uses her as a shield from an incoming cake. She then angrily declares him to be "a royal pain" and splatters frosting all over him.
Sweetie Belle is introduced as Rarity's little sister in Stare Master. Her clumsiness, paired with an insistent willingness to help, tests Rarity's patience and she eventually asks Sweetie Belle to let her work in peace. Sweetie Belle "borrows" important supplies from Rarity in Stare Master and The Show Stoppers, using her most expensive fabrics to make amateurishly-stitched costumes for her friends. Even though Sweetie's eagerness to help usually unintentionally causes messes, she and Rarity truly do love and care for each other. At the end of Sisterhooves Social, they agree to embrace and love each other's differences, and send a letter to Celestia describing how being sisters is mainly about having fun, but that it also requires compromises and work to keep a strong relationship. In Sleepless in Ponyville, Sweetie Belle invites Rarity to go on a camping trip with Apple Bloom, Applejack, Scootaloo and Rainbow Dash. Rarity refuses at first, since she does not usually enjoy being around nature, but she reluctantly agrees to go after seeing some disappointed faces made by Sweetie. Though Rarity is not necessarily mean towards Sweetie Belle, she makes her carry all of her luggage on the trip and wait on her after they set up camp. Later, Rarity shows compassion towards Sweetie Belle, such as letting Scootaloo carry her luggage in order to give Sweetie Belle a rest, comforting her when she's frightened by Rainbow Dash's ghost stories, and happily racing with her at the end of the episode.
In Sisterhooves Social, Rarity and Sweetie Belle's parents make a brief appearance. The two have a mid-American accent and are carefree, with personalities that are vastly different from Rarity's. Her father is a white unicorn (shown for the first time on My Little Pony: The Elements of Harmony page 145, shown for the second time on My Little Pony: Friendship is Magic Issue #9 page 16, and shown for the third time in Inspiration Manifestation) with a brown mane and mustache and very thick eyebrows compared to other stallions. Her mother is a pink unicorn with a body and mane design similar to that of Mrs. Cake, although her mane color is a slightly lighter shade of Rarity's royal purple mane.
Rarity keeps a cat named Opalescence, who is supportive in Suited For Success. In Stare Master, however, Rarity seems to have trouble with the cat and asks for Fluttershy's assistance. In The Best Night Ever, Opalescence scares away the mice that Twilight Sparkle had turned into horses to pull their carriage to the Gala. Opal makes her first season two appearance when Rarity dresses her with her shrunken wool sweater in Sisterhooves Social. Her next appearance is in May the Best Pet Win!, where she is shown as one of the trials for Rainbow Dash's potential pets. She appears again in Sweet and Elite, accompanying Rarity on her trip to Canterlot where she tries to remind Rarity to work on Twilight Sparkle's new birthday dress when Rarity becomes too caught up in social obligations. When her friends come to her suite at the castle, Rarity quickly douses Opal in water to support her made-up excuse she gave as to why she couldn't make it to Ponyville for Twilight's birthday, much to Opal's dismay.
Spike develops a crush on Rarity the moment he sees her in Friendship is Magic, part 1, calling her "beautiful". He admits to having a crush on Rarity in Green Isn't Your Color and is seen wearing a shirt that has a picture of Rarity superimposed on a heart. In Owl's Well That Ends Well, Rarity calls Spike "simply amazing" and gives him a bow tie laden with jewels.
Spike and Rarity's relationship becomes stronger in later episodes. In Secret of My Excess, Spike generously gives Rarity a fire ruby that she covets. In gratitude, she kisses him on the cheek and calls him "Spikey-wikey." During Spike's birthday party, they affectionately rub their cheeks together. Later in the episode, when Spike returns to normal after growing into a monstrous dragon and he and Rarity plummet to the ground, Spike very nearly confesses his feelings for her, but Rarity stops him mid-sentence and gives a teary smile at him, and Spike smiles back. After they are rescued by Fluttershy and Rainbow Dash, Rarity calls Spike her hero and kisses him on the cheek again.
Rarity shows a more caring and sensitive feeling for Spike in Dragon Quest and still calls him "Spikey-wikey." She stands up for him when Applejack, Pinkie Pie, and Rainbow Dash pick on him and when Spike decides to join the dragon migration, Rarity tries to change his mind, telling him that she doesn't want him to get hurt by the other dragons. Later, she even threatens to hurt the older dragons if they harm Spike. In Spike at Your Service, Rarity pretends to eat Spike's disastrously burned pie to make him happy. In Simple Ways, Spike helps Rarity in her attempts to win the heart of Trenderhoof, despite his own feelings for her.
In Inspiration Manifestation, Spike assists Rarity as she designs a puppet theater for the Foal and Filly Fair. She thanks Spike for his help, defining him one of her dearest and most supportive friends and calling him her "favorite dragon". When Rarity's theater is met with harsh reception and she falls into a depression, Spike helps by finding a spell from a hidden spell book to bring Rarity's ideas to life. However, Rarity is corrupted by the spell, and Spike worries that telling her to stop will cost him her friendship. Spike soon tells Rarity the truth about her actions, breaking the spell, and Rarity tells Spike he should never be afraid of telling her the truth, and the two share a friendly hug.
In some situations, Spike is even submissive in his devotion to Rarity. In Green Isn't Your Color, he gladly offers his body as a pincushion for Rarity to use while she designs a dress. In Party of One, he takes out Rarity's garbage and addresses her as "most beautiful one". He looks at her lovingly even after she says he smells "like a rotten apple core that's been wrapped in moldy hay and dipped in dragon perspiration." In Rarity Takes Manehattan, Spike carries Rarity's bags to the train station and through the streets of Manehattan. During the song Generosity, she buys him a carrot dog as a sign of gratitude.
In Castle Sweet Castle, Spike is seen waking up holding a beanie version of Rarity. In Scare Master, Rarity, out of fear of Flutterbat possibly about to attack, caresses Spike.
In The Cutie Re-Mark - Part 2, in an alternate timeline where Equestria is ruled by Nightmare Moon, Spike attempts to talk to Rarity, who is working as Nightmare Moon's royal decorator, but since she does not recognize him, she snubs him.