Kelly Keefe is a tough-as-nails daughter of an Army officer and West Point alumnus, who takes over the life of Carl. 
Kelly's father hosts a ball for military school and things are good, as she meets Carl Gallagher. She reveals that she is readying to go to Annapolis school before she comes onto him. They sneak into her father's liquor cabinet and nearly have sex but she passes out after puking. Kelly wakes up and accuses Carl of filming the encounter before chasing him and he hides in her father's study. Her father is there and Carl tells him what occurred but he is promptly kicked out. Later on, she tracks Carl to his home (since she looked him up in the roster and his passcode was his address) while Carl is outside burying a dead dog before Kelly catches his attention. She returns his phone that he left behind and sees he didn't film her but his ex-girlfriend Kassidi. Carl tells Kelly he didn't do anything to her, as she apologizes for her misunderstanding and kisses him since he was single.
Kelly later visits the house again, where she teaches Carl fighting moves and helps with teaching his brother Ian to help him survive prison.
Kelly comes come over, as Carl was excited as he thought they'd have sex as he moves in his father's old room since he moved out. Kelly arrives to help with his lessons and he is disappointed she only wanted to study and has Liam help. While going over military assessments, she watches as Carl is informed by Debbie of Fiona's hardships with a car accident and learning of Ford's marriage. Later on, Kelly and Carl keep studying and she is exasperated with Carl's lack of knowledge on the subjects, though lets it slip that she wanted her boyfriend at West Point. Carl is surprised by being her boyfriend and she confirms this as he decides to try harder with his childhood helping him excel.
In The Apple Doesn't Fall Far From The Alibi, she and Carl are still seeing each other and fooling around in the tent so her father doesn't catch them.
During BOOOOOOOOOOOONE!, she decides to take up a more assertive stance towards her future by taking Carl to her home. Kelly forms her own vision board by telling her father and boyfriend that she still wants to go to school and see Carl. She also abolishes her father's rules and makes a list of demands to him. After ending her rant, she tells Carl that they will have sex in her room while her father sheepishly allows this.
In Los Diablos, she continues seeing Carl and takes enjoying life at the Gallagher House. She later helps Debbie get from under the house when she's trapped. She spanks Debbie's behind and turns off the gas to the house. Debbie develops an attraction to Kelly.
During The Hobo Games, she congratulates Carl on his job and wishes him luck as she and Debbie hang out. Kelly sends Carl a picture and he worries because of their closeness (and Debbie's previous track record of being rapacious and misinterpreting of the nature of certain aspects of prior relationships i.e. raping her first boyfriend Matt while his was drunk and unconscious and tricking her next boyfriend Derek into impregnating her to force him into a "loving" relationship).
In You'll Know Bottom When You Hit It, Kelly breaks up with Carl for believing she'd be attracted to Debbie and not trusting her.
As of Lost, she helps Carl and Debbie in bringing an injured Frank in his home though pukes at his bone out. Kelly spends the day with Debbie and her daughter to go shopping for supplies with her new school. While sleeping, Kelly cuddles with Debbie on the couch. Debbie wakes up and takes the chance to kiss Kelly and she unconsciously kisses her back until she wakes up and rejects Debbie. Kelly frantically tells Debbie they can't be together since she is straight, while realizing Carl was right to be suspicious. However, Kelly maintains the thought of being friends and leaves, while Debbie is devastated.
During Found, Kelly is at her home where she is woken up by a noise and spots two figures vandalizing her truck and shouts at them before they run away, though Kelly knew who it was. The next day, she finds Debbie on the streets and confronts on her acts, stating she thought they were friends. However, she is silent when Debbie reveals of what Carl is planning to do and watches her storm off. At Carl's job, Carl talks with his manager before he notices Kelly's truck and quickly runs away. However, Kelly storms in and tackles him down as she berates him for being willing to throw his life away. Kelly straps Carl's hands to his back as she takes him, while telling Carl's boss that he quits and will go back to school. Carl is loaded up in Kelly's truck and taken away while his manager watches the scene, she comments on how Carl has a real lady keeping him in line, and decides to resume their relationship.
In Sparky, Kelly is telling Carl about her experience to military school camp while secretly being jealous of his interest in Anne. She invites Carl out for an outing, Kelly does remain jealous that he is more interested in. Anne. However it is implied that she is cheating on Carl when she mentions her experiences with a classmate named Mitch, while being hinted to have an STD. When they return home, Kelly comes into an argument after it is revealed that Frank used Carl sperm to impregnate his ex-girlfriend Ingrid who has given birth to twins. Ingrid’s ex husband Randy tries to have Frank keep the babies. Kelly tells Randy not to let Carl or Frank have the babies because Kelly labels Frank as the addict and a loser while Carl is doing too much to have kids. In the end, Frank keeps the babies. Holding one of Carl’s babies, Kelly goes along with Carl's scam because Frank has has never lost at scamming.
- Kelly is a capable fighter, easily scaring her father and Carl who are both skilled.
- She is one of the few characters not put off by the Gallagher life.
- She is Carl's fourth real girlfriend.
- She is Carl's second girlfriend to cheat on him, after Dominique
- Apparently she has had STDs before.