Kevin Ball (born Bart), known simply as Kev, is the bartender at Frank's favorite bar and the Gallaghers' neighbor and friend along with his long term girlfriend Veronica. Kev is a good man and can usually be persuaded to give Frank drinks on credit or cash his disability checks for him but that doesn't mean he loves living near the Gallaghers all the time. Fiona often convinces Veronica to help in some way, such as allowing the youngest Gallagher to use their bathroom, but V finds it easier to keep these things from Kev, who can often be heard uttering the words "fucking Gallaghers". Kev and Veronica are known for having the most loving and committed relationship on the show as well as their particularly adventurous sex life.
In the fourth episode of the first season, Casey Casden, Kev told a flirty girl at the bar that he was getting married as a way to get her to leave him alone. Unfortunately, Frank overheard and thought Kev was serious. Ignoring Kev's panicked attempts to shut him up, Frank announced the "happy news" to the bar, including Veronica's mother Carol. A worried Kev then spent the next few hours getting extremely drunk and talking to an ecstatic Carol. Hearing how much Veronica loved him and perhaps realizing the strength of his own feelings, Kev decided to drunkenly propose to V instead of admitting the mistake.
Queue the whirlwind party at the Gallaghers' house and the congratulations. But Fiona noticed Kev looking withdrawn and unhappy, making only a half serious remark she was shocked when he admitted that he was already married!
In the second season, Kevin and Lip Gallagher ran a successful side business selling beer, cigarettes, marijuana, soda, candy, and taking book out of a run down ice cream truck. At the end of the first episode, Kevin became a neighborhood hero when due to help from his foster kid Ethel he was forced to burn most of the marijuana plants he had been growing in the basement of the Alibi Room. When foster daughter Ethel and her son Jonah left Kevin was heartbroken and often thought about her and how much he wished he had children of his own with wife Veronica.
In Season 3 episode 2 Kevin's wife Sheryl makes an appearance with her son Kyle who may not be his (not yet mentioned during the episode). Veronica stays over at the Gallaghers' house after sometime later in the same day. Kevin tries to cope with the reality Fiona get upset about the whole thing and confronts Kevin about not picking Veronica. Kevin had gotten divorce paper around this time. Kevin chooses Veronica and the his wife was nothing more than a memory but he's only trying to get to know his kid and be his father and Fiona and Veronica start to laugh possibly due to accepting Kevin's apology. This reality of him being the father becomes proven false when Sheryl walks in the Gallaghers' house tries to ask whats they were laughing about. She then asked if it was about her which was answered right away and out of anger from hearing Kevin's decision and Fiona answer to which she insults her, Sheryl reveals that her son is really her sister's son, not his during dinner time. Veronica then gets upset and begin to fight Sheryl. Veronica forces Sheryl to sign the divorce papers. Sheryl drives off alone leaving Kyle behind. Kyle asked if he could call his real mom instead of going with his aunt.
He continues to have sex with Veronica in an attempt to have a child. He and Veronica decide to give his sperm to Carol in order to have a baby after trying to find a donor and finding out V can't have a baby.
In Simple Pleasures, Veronica is revealed to be pregnant with Kevin's baby, surprising the two parents since Veronica was said to be close to infertile.
In My Oldest Daughter, Stan, the previous owner of The Alibi Room, has left Kevin full ownership of the bar in his will. Kevin, feeling unfair on behalf of Stan's biological son, Alan, offers to give back the bar, but Alan purposes that Kevin should give him $500 for the next two years as a form of rent. Kevin agrees and is then stated as the new owner of The Alibi Room.
Kev and Veronica have difficulties becoming parents. While Kevin is totally thrilled to be a dad, V misses the freedom of being single and desperately wants Kev's attention. They actually go through a break up period of time when they try to live separate lives.
While Svetlana is working at their bar, Kev spills about her immigration status unknowingly to a federal agent. Rather than loose Svetlana, Veronica decides to marry her so she can stay in the US.
Svetlana, Kev, and Veronica enter into the throupple relationship. However, Svetlana's husband from Russia shows up. She lies and said he is her father. She also steals the bar from Kev and Veronica when they thought they were signing adoption papers for their children, they were actually signing over the Alibi bar to the new owner, Svetlana Fisher.
In the 8th season, he questions his sexuality.