Kelly is part of the popular crowd and starts off the film as Brandon's girlfriend. On the bus to K-12 Sleepaway School, she makes fun of Cry Baby with the other students. When Brandon boards the bus, Cry Baby instantly falls for him, which angers Kelly.
When Brandon asks Cry Baby for an eraser in class, she becomes jealous that Brandon didn't ask her for one. She writes a letter to Cry Baby saying "You at recess" accompanied by a stick person and a tombstone. At recess, Kelly sees Cry Baby and Angelita talking to her boyfriend. She storms up to Cry Baby, while pushing others out of her way, and slaps her repeatedly. When she pulls out a knife and draws blood from Cry Baby's arm, Cry Baby's powers activate and she levitates and attempts to strangle Kelly with her braids. As this is happening, Ms. Daphne sees what is happening and stops the fight.
Kelly is also partially responsible for Fleur's bulimia, as she threatens her with removal from the friend group if she doesn't maintain a certain physique.
When Leo, the Principal's son, stops the food fight in the cafeteria and asks who is responsible for the situation, Kelly informs him that Cry Baby was the one who started it, resulting in her being sent to detention.
At the school dance, Kelly is dumped by Brandon, who left her for her friend Lucy. She is shunned by her group of friends as she exclaims that she made them and that they are "nothing without [her]", and she is left with nobody. Her fate remains unknown, as she was the only known student who remained in the school when Cry Baby and Ben made it disappear.
Kelly is very insecure and narcissistic. She hates being touched by anyone she finds less important or popular than she is. She is shallow and conceited, being more concerned about the appearance of her friends rather than their mental health. Kelly is a bully by nature, snapping for seemingly no reason and acting cruel without any provocation. She is also prone to explosive reactions, even becoming violent and visibly scarring those who anger her. She is very protective over her boyfriend and is not at all bothered by betraying old friends or screwing strangers over.
In Alternative Press magazine, Kelly was revealed to be Aries sun and rising. Her zodiac sign was described as positive, straightforward, intellectual, philosophical and adventurous, but also as careless, tactical, impatient, superficial, inconsistent and overconfident.
She said in the Artist Spotlight Stories that Kelly projects her insecurities onto other people, Cry Baby as an example.
Kelly has medium-length blonde hair and blue eyes. She is of about average height and has a light skin tone. She is usually seen wearing the school's uniform. At the dance, Kelly wears a golden U-neck dress.
- According to Melanie, Kelly's hairstyle changes the least throughout the film, symbolizing how she will not change as a person.
- Melanie has stated that Kelly was inspired by a real person who bullied her as a child.
|Featured Tracks||Wheels On the Bus • Class Fight • The Principal • Show & Tell • Nurse's Office • Drama Club • Strawberry Shortcake • Lunchbox Friends • Orange Juice • Detention • Teacher's Pet • High School Sweethearts • Recess|
|Credit Track||Fire Drill|
|Characters||Cry Baby • Angelita • Fleur • Celeste • Magnolia • Leo • Ben • Kelly • Blue Boy • Brandon • Bunny Doctor • Dean • Ms. Daphne • Mr. Cornwell • Ms. Harper • Ms. Penelope • Miss Victoria • The Principal • Lilith • Biology Teacher • Phillipe|
|Extras||Film • Merchandise • Assignments • Removed Songs|
|Locations||K-12 Sleepaway School • Cry Baby's House|