The conflict between K.C. Guthrie and his basketball coach, Coach Carson began in season 9. At first, K.C. saw Carson as a role model and father figure. However, Carson's true colors were shown when he gave K.C. beer, had him watch porn, showed him a gun, and tried to set him up with a prostitute. K.C. later calls him a pervert and a loser and tells him that everybody will know what he has done though Carson claims that he never touched him. K.C. later reports Carson to Archie Simpson and Daphne Hatzilakos about the gun and other stuff that Carson has done. Carson is later arrested.
In Close to Me, Carson is seen helping K.C. with his basketball skills. Later at the game, Carson pulls K.C. out of the game and K.C. believes that its because he "sucks." He starts trashing the locker rooms. Later, Carson tells him that he still wants K.C. on the team though he tells K.C. that he has to clean up his mess from the locker room.
In Heart Like Mine (1), while K.C. is dealing with his relationship with Clare and his feelings for Jenna, Carson gives him the idea to break up with Clare and go out with Jenna, which is exactly what he does. K.C. also tells Carson of how both of his parents are in jail. At the Athletes Banquet, Carson rewards K.C. for most improve player. Later, after Alli makes a comment to K.C. and Jenna of how they hurt Clare, Carson gives K.C. his key room so he and Jenna can be alone. While K.C. and Jenna are making out, Carson walks in and stares at them. Jenna then notices and stops kissing K.C. K.C. turns around and yells out embarrassed "Coach!" Carson says that he needed something. Jenna, feeling uncomfortable with Carson, decides to head back to the party while K.C. stays with Carson. Carson decides to call the group home to let K.C. stay for the night. Carson then gives K.C. beer. Later, K.C. talks to Carson that he doesn't know anything about sex and Carson then decides have K.C. watch porn. While they are watching porn, K.C. looks uncomfortable.
In Heart Like Mine (2), K.C. wakes up and has a hangover. Carson tells him that he just has to drink some water. K.C. looks like that he's uncomfortable. At school, after when K.C. throws up from drinking, Jenna asks if he is okay. K.C. admits that Carson gave him beer. Jenna tells him that there's something wrong with Carson but K.C. tells Jenna that she should be thanking him since he made him broke up with Clare. Jenna looks upset and walks away. After a basketball practice, he and Carson head back to the hotel. Carson then shows him to a gun he keeps and tells him that he has to be the fear which freaks K.C. out. Later, back in the hotel room, Carson calls Stacie over and K.C. recognizes her from the carwash. As Stacie sits down, Carson then has K.C. sit down and tells him to relax and that she's a "pro." Starting to get scared, K.C. realizes that Stacie is a prostitute. K.C. begs Carson not to make him go through it but Carson doesn't care. K.C. then runs out of the room. Later, at school where there's another basketball game, K.C. takes Carson's gun from his car and goes to the locker room. Carson then enters. He asks K.C. why isn't he playing and K.C. tells him that he's not playing. They get into an argument and Carson says "All we did was watch a little movie." K.C. then starts yelling at him and says "You're a pervert. A loser. And everyone is going to find out." Carson then says "Nothing happened. I never touched you." K.C. then goes to Simpson and Hatzilakos and shows them Carson's gun. Hatzilakos has Snake get the police. Hatzilakos asks K.C. if she knows to anything else and K.C. starts talking. Later, Carson is shown being escorted out and then as he sees K.C., he glares at him. The next day, K.C. goes to Jenna and tells her that she was right about Carson. Jenna then comforts K.C.
In In Your Eyes, K.C. tells Clare about what Carson did to him.
In 99 Problems (1), K.C. is hesitate to join the basketball team because of his previous situation with Carson. However, Jenna tells him not let some pervert get to him.
In Better Off Alone (2), while K.C., Fitz and Bianca DeSousa were drinking, it is revealed that K.C. said that to them that Carson tried to hire a hooker for him and Fitz says that he wants on that team.
- They both like basketball.
- Carson was the one who told K.C. to break up with Clare and go after Jenna.
- He made K.C. drink beer, watch porn, and tried to make him have sex with a hooker against's K.C.'s will.
- Carson showed K.C. his gun which K.C. then reported him for it.
- K.C. saw Carson as a father figure until Carson is shown for what he really is.
- K.C. stole Carson's gun and brought it to school.