Opalescence

Opalescence, or Opal for short, is Rarity's cat. She is introduced in the episode Suited for Success.

Character design and personality
Opalescence looks like a typical Persian cat, with white fluffy fur, a wide face, and shortened muzzle. She wears an opal-studded collar around her neck, and a purple ribbon on the top of her head. Whenever Opal is focused on throughout the show, her actions are accompanied by a brief harpsichord trill.

She is irritable and often yowls and hisses in anger at her owner, Rarity, and other ponies. But she seems to have a good time playing in the park with Rarity on their pony-pet-playdate. Opal seems to have a fashion sense; when Rarity reveals her finished first dresses to Twilight Sparkle and the others, she is seen happily playing with them, while after Rarity unveils the girls' custom dresses, Opal shows disgust. And when Rarity puts off work on Twilight's dress in Sweet and Elite, Opal attempts to remind her.

Suited for Success
Opalescence first appears in the opening shot of Suited for Success. Rarity has a "conversation" with her as one would with a pet, thanking her for her assistance and asking for her advice, while Opal seems bothered and annoyed by being given things to carry and being carelessly flung off the fabric that she was sitting on. Rarity confides in Opal throughout the episode, but Opal only hisses and mews in return. When Rarity locks herself in her room after her failed fashion show, Rainbow Dash strands Opal in a tree to lure Rarity out of the room; Opal doesn't look pleased at all from the situation, as she shakily hugs a branch while mewing in fear to rescue her.

Other appearances
Other than Suited For Success, Opal is featured briefly in Stare Master, Owl's Well That Ends Well, The Best Night Ever, Sisterhooves Social, May the Best Pet Win!, and Sweet and Elite. She swipes and chops off a lock of at Sweetie Belle's mane and offers a smug look, after Sweetie Belle suggests that her special talent might be caring for animals, in the episode Stare Master. Opal is briefly seen when Spike takes a stuffed toy mouse from her in Owl's Well That Ends Well, which he uses as a ketchup-bloodied carcass in his attempt to frame Owloysius for its killing.

When Twilight Sparkle turns Fluttershy's mice into stage horses for the Grand Galloping Gala in The Best Night Ever, Opal spots the rather unconvincingly all-the-way changed mice and leaps into the air to pounce on them. Fluttershy, afraid for the safety of her little friends tries to stop her but to no avail. Opal has her claws on the one of the "horses" and they run off in a fright, knocking the cat off.

Opal is pitted by Rainbow Dash against some prospective pets as a test of "guts" in May the Best Pet Win! The animals quake in fear when Dash dares them to take away Opal's favorite toy, a stuffed mouse. One of the contestants, a butterfly, successfully mesmerizes Opal and whisks away her toy. Tank, the tortoise, tries to trap Opal in her carrying case by flipping it over her, but she gets out of the way in time and fiercely scratches at his shell. Near the end of the episode, Tank does succeed in taking away the toy from Opal while she is busy scratching his shell.

Opal accompanies Rarity to Canterlot during her stay at Canterlot Castle in Sweet and Elite. Opal indulges in much of the royal city's many regal splendors with Rarity, and when Rarity decides to create a new dress as a gift for Twilight's birthday party, Opal tries to keep her focused on her work (As Rarity was also trying to get in with Canterlot's sophisticated crowd at the same time). Ultimately however, the two stay in Canterlot longer as Twilight and the others unexpectedly show up to host the party there since Rarity lied that she had to stay to take care of a "sick" Opal. She ends up soaking Opal in water to maintain her cover, as she tries to attend both Twilight's party and a sophisticated social next door. Fluttershy gives the "poor baby" her usual tender love and care, hoping to make her "better".

Gallery

 * Opalescence image gallery

Opalescence Opal