Sour Sweet

Sour Sweet is a female human and one of the Crystal Prep Academy Shadowbolts in My Little Pony Equestria Girls: Friendship Games, and a foil to the main heroes in both Friendship Games and Dance Magic. She can be an easily-frustrated person, and among the most competitive members.

Equestria Girls: Friendship Games
Sour Sweet appears in My Little Pony Equestria Girls: Friendship Games as a member of Crystal Prep Academy's sports team, the Shadowbolts. She complains when Twilight Sparkle accidentally cuts in front of her on the bus to Canterlot High School, and she continues to act hostile towards her after Twilight offers to let her go ahead.

Sour Sweet participates in the Academic Decathlon of the Friendship Games, being paired up with Sunny Flare during the woodcutting portion, and failing the spelling bee portion.

Principal Cinch assigns her and Twilight to the archery portion of the Tri-Cross Relay, where she swiftly and expertly hits a bull's-eye. She is infuriated when Twilight struggles to keep up and wastes their team's early lead, and she gives her a backhanded compliment for taking their opponent Applejack's advice. After Twilight finally hits a bull's-eye, Sour Sweet becomes visibly disturbed when Twilight's dog Spike demonstrates the ability to speak and congratulates her.

During the final event, Sour Sweet joins Principal Cinch and the other Shadowbolts in pressuring Twilight into releasing the magic she collected throughout the Games, and she watches in horror as the magic transforms Twilight into the monstrous Midnight Sparkle. As Midnight slowly destroys the world around her, Sour Sweet and her teammates help save their fellow students and the Wondercolts, pulling up one of Crystal Prep's students with Pinkie Pie's assistance.

After Twilight returns to normal, Sour Sweet remorsefully admits the Shadowbolts' responsibility for what happened, accepting some of the blame before bitterly pinning most of it on Cinch. She and Upper Crust are later shown speaking with Dean Cadance before leaving with the rest of Crystal Prep's students.

Personality
True to her name, Sour Sweet has a bipolar personality where she alternates between being sarcastic and rude (sour) and obnoxiously nice (sweet). This trait is more subdued in her later appearances. She acts mean towards Twilight throughout Friendship Games, irritated by her thoughtless and clumsy behavior, which she believes will cost her team's victory in the games. Much like the rest of her school, Sour Sweet is highly competitive and confident in her athletic skill, and she is willing to use peer pressure against Twilight to manipulate her into using magic for Crystal Prep's benefit. After this ends up endangering both schools, Sour Sweet becomes remorseful and helps rescue her classmates alongside Canterlot High's students.

Equestria Girls: Dance Magic
In the half-hour special Dance Magic, Sour Sweet appears with Lemon Zest, Sunny Flare, and Sugarcoat competing with the Rainbooms in a music video contest. She appears to act as the de facto leader of the group in this special.

Role in the series
Though she doesn't appear much in the series, her Equestrian Pegasus counterpart appears in Speedster's Marathon as she joins Indigo Zap's Equestrian counterpart in a Pegasus Marathon and helps Rainbow Dash defeat The Speed King by taking his Shoes of Hermes and give her a fair advantage against his unfair disadvantages. She claims her bipolar depression comes from her father, who was good at being a good cop-bad cop interrogator.