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.
Kev loves being a father, as seen when he was happy to hold his son Dominick and was sadden that he couldn't raise him full time. However, he was even more happy to have daughters and doesn't waste time, in bonding with them as well as his visiting his son.
Unlike most characters, he has a good heart as seen when he worried about his foster child Ethel and when he comes to the aid of his friends even Frank. He showed this side again after crippling a neighbor and accidentally causing his death. While Kev took part in throwing Frank off a bridge, he felt guilt when seeing him survive and being in a wheelchair and was the only person that felt that way. He is even seen making amends with him by voicing relief to see him on his feet and bringing him to the hospital after he has liver problems. Kev also appreciated Frank giving him an ice pack for his recovery.
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 But Fiona noticed Kev looking withdrawn and unhappy, making only a half serious remark she was shocked when he admitted that he was already married!
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.
Kev bore witness to the return of Peggy Gallagher and is amused with watching her torment Frank. However, he is surprised when she nearly shoots Shelia but misses.
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 as 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 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. After Sheryl does it, she flees the house and 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 Veronica can't have a baby.
Kev learns that Carol had became pregnant with his child and is happy.
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, died and 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.
When dealing with money problems, he allows Mickey to have Svetlana and her friends service the patrons. This also saves Kev from being attacked by Alan's gang by letting them be with the women.
Later on, Kev, Kermit, and Tommy are invited to Sheila's home by Frank's oldest daughter Sammi as a way to get him the bar in his recovery. This brought a smile to Frank's face.
Near the finale, Kev becomes the father of a son named Dominick with Carol who will raise the child herself since she was lonely, despite Kev's sadness at not being with his son. However, he moves past his depression when Veronica gives birth to twin girls Amy and Jemma whom he becomes the proud father of.
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.
Kev goes to stay at Lip's college dorm room and begins to have sex with most of the college girls and runs a business with Lip and his friends. When they are nearly caught with the act, Lip forces Kev to leave and be with his family. Kev does so and makes amends with Veronica.
While Svetlana is working at their bar, Kev spills about her immigration status unknowingly to a federal agent. Rather than lose Svetlana, Veronica decides to marry her so she can stay in the US.
Kev also cuts the wires to the motorcycle of his neighbor. However, he feels guilt when the latter is paralyzed and blames their neighbors. He later confesses his deed to the latter when he goes out to burn down a house. After Kev reveals, the man turns his rage on him but is burned to death after dropping a flaming bottle on himself.
He took part in throwing Frank off the bridge after he ruined Fiona's wedding. After the act, he leaves the area with everyone.
After a month in Hiraeth, Kev, Svetlana, and Veronica enter into the throuple relationship, something that excites him. The trio take care of their kids together and run the Alibi very well with good business flowing. Kev is later surprised to see that Frank survived the fall and screams at the sight of him returning in a wheelchair, while casually asking for a drink. Kev then talks with him and learns Frank was only in a coma once he was pulled out the river, not dead as Kev thought and the chair is temporary before he recovers from his injuries. Kev is worried when Frank shows no memory of how he ended up in the river. However, he is scared when Frank recalls him having a hand in throwing him off the bridge before he curses Kev and the others for what they did to him and leaves out the bar furious. Kev was notable for being the only person who felt guilt for throwing Frank away after seeing his condition.
He is at the Gallagher house in Swipe, Fuck, Leave and is somewhat relieved to see that Frank has recovered from his injuries, voicing to the latter on how good it is to see him back on his feet but is met with a glare by him. Kev is very worried when Frank promises to get even with his family for nearly killing him and insulting him since he returned. Kev watched Frank brush aside Lip and Ian's attempts to stop him from taking Liam, since he is the only loyal child he has. Kev seemed to support Frank's choice, as he thought Frank in his own way can care for him, though the older Gallaghers tell him there is seemingly no chance.
In Home Sweet Homeless Shelter, Kev, V, and Svetlana start a business which consist of a topless maid service. However, they deal with the sudden arrival of Svetlana's estranged intimidating father. Kev is later surprised to see Frank opened a homeless shelter on their block and sends them away since they have shown him how they felt.
In I Am a Storm Kev continues his relationship with Veronica and Svetlana. He talks with V on her feud with Fiona and tells them that he knows they will make up. Unlike V, Kev is comfortable with Lana's father watching the kids, even after a few scares.
During Own Your Shit, he is now wondering on what place he holds in his growing family when Lana moves to adopt the kids. However, Kev walks in on Svetlana having sex with her supposed father.
As of The Defenestration of Frank, he soon confronts her on this along with. It is revealed she lied about him being her father and he is really her husband from Russia. Kev notices Lip's change and tries to persuade him but he tells Kev to stop pushing his expectations on him and he backs off.
It is shown You'll Never Ever Get a Chicken in Your Whole Entire Life, that Kev is reaching his limit when it is hinted that Lana killed her husband when covered in blood.
In You Sold Me the Laundromat, Remember?, Kev sees Veronica is too influenced by Lana and decides to move out of the house for a while. He stands his ground to both by making a decision to help Fiona without consulting his wife and ordering her to get their children from a supposed relative of Lana. This intimidates Lana and V who complies with the order.
In Ouroboros, he stays at the Gallagher House on the couch and witnesses the return of Monica. Kev tries to get the Gallagher children to give their mother a chance, since she was nice to him. Kev goes to therapy with his wife and Lana, where they talk out their issues. When returning, Kev thinks everything is okay until it turns out Lana has stolen 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.
As seen Ride or Die, Kev gets a job as a bar tender at a gay bar after he harasses the manager with guilt to do so. Kev does well by acting like a dancer and brings in more money.
Much later in Happily Ever After, Kev continues his job and is relieved when Veronica reclaims the bar and has Lana arrested.
During Requiem For a Slut, Kev is present at the hospital when the Gallaghers learn of Monica's death. At her funeral, he watches the family give moving words about her. He soon leaves and goes to the Gallagher house, where he watches them have fun and accept Frank back again.
In We Become What We... Frank!, he has a breast cancer scare after he is told of a lump on his chest. Kev begins to worry and starts readying for the end. He is also one of the few people to welcome Frank's change and cheers him on for it.
When going to the doctor, he is relieved to hear that he is alright but hears that he might need to track his family to see if it was genetic.
Angered that Svetlana essentially betrayed her and Kev, Veronica tells the police that Svetlana was harboring illegals, with that said, Svetlana is put into jail. After Svetlana is put into jail, Kev and Veronica soon realize how important she was to the alibi, as not only does she legally own it, but she also is the one who put the most work and effort into it. Knowing this, Veronica makes a deal with Svetlana, with the profits from the bar being 50/50, meaning that Svetlana gets 50, because of the effort she puts into the Alibi, while Kev and Veronica get 50.
Kevin also meets his biological family in Kentucky, and discovers they left him at a gas station on purpose due to an overcrowded family having no income to support him. He forgives them after he learns he was the only successful member. Kev also discovers in this season that Veronica likes to be dominated sexually, hence her attraction to Svetlana. Kevin experiments with domination in the bedroom, which bleeds into his personality, especially regarding his behavior with Svetlana.
Kev spends most of his time working on the Alibi and promotes his bar's status as a non-sexual area that brings much popularity.
He continues running his bar and on two occasions brought Frank to the hospital after he passes out from urinating black.
Kev and Veronica later put their daughters in pre-school but since only one spot was opened, they are forced to be able to put one person in it.
He also desires to have a new child with Veronica, who is against the idea but gets around to the idea. They soon adopt a child named Santiago and Kev is happy to finally have a son, despite him not speaking English. He is even more delighted the latter plays baseball, something makes him dream of his potential. Later on, he and his family deliver a drunk and passed out Fiona to the Gallagher Family and lay her on the couch.
Very soon, he and Veronica track down Santiago's birth family after learning they were nearby. Kev unintentionally alerts the cops of Santiago's father being illegal and watches him escape by running into a nearby alley.
He later helps V with getting their daughters into not bullying Santiago by failingly trying to relate about his experience with his foster family. Soon they reunite Santiago with his sister, Kev is happy at this but depressed as they plan to return to their home country than stay.
After Santiago leaves, Kev has to get a vasectomy at V's insistence but he bails out at the last minute. However, V finds out and forces him to get the procedure.
In You'll Know Bottom When You Hit It, while taking time to heal from the surgery, the city experiences a blackout and Kev can't get ice without power. Because of an investment V made, they have a barbecue. During the party, Kev is given free ice for his recovery by Frank for his vasectomy as a show of good will, something that elates him.
Eventually, in Lost Kev and Veronica's ruse of the twins switching places is exposed when Amy and Jenna are both shown to the teachers. However, rather than take it to court, Kev and Veronica are given the option of having Kev dress up as Jesus for their parade. They state he has the physique for the role but has to carry a large cross on his back. Wanting to avoid trouble, Kev agrees and starts practicing for the role by carry the heavy cross down his block where he is spotted by Carl and Debbie.
During Found, he continues practicing for his role as Jesus but struggles with the weight. He later attends Fiona's going away party, even though she left already and they celebrate anyway. When Lip sits on the stairway, Kevin joins him and Lip reveals his concerns over Tami's pregnancy and wonders if he'll be a good dad and asks Kevin for advice. Kevin encourages him and decisively tells him that he'll do great and that it doesn't matter if Frank didn't raise him right.
In Gallavich, V notices Kevin hiding away money and lying about it. Later, he helps set up Ian and Mickey's wedding and confiscates the polka hall's "Fag Fixer" bat so that no one can use it on Ian and Mickey; when the bartender looks for it, Kevin smugly shows the bat to the man. Later, V confronts Kevin over his lies and he reveals that he bought V an engagement ring and was waiting for the right moment to ask her. V happily accepts his proposal though Kevin must find and get divorced from his ex before they can marry.