Life with Derek is a half-hour comedy series about a modern blended family, with two type-A 15 year-olds, Casey (Ashley Leggat) and Derek (Michael Seater). Each episode is an alpha-teen comic war between two self-obsessed teenagers in a take-no-prisoners fight for control of their house, their school, and their world.
As penance for his latest misdemeanor, Derek is told to coach Lizzie in hockey. Casey gets jealous of Derek's relationship with her little sister so agrees to coach Edwin in the art of attracting the team captain.
Derek couldn't case less that Casey and Sam are always breaking up and getting back together, until they break up for good and Sam's ability to play hockey goes down the tubes.
Casey is disgusted with her fellow students' apathy about the upcoming school election. Corey Plunkett expects to be a shoe-in, until Casey convinces Derek to lend his cool factor to the process by running himself
Derek's band is so desperate for a singer that they ask Casey to join; even though she's more folk than metal and thinks they're a bunch of posers. George, remembering his rock 'n roll youth, longs to join the band himself.
Casey, compromising all her principles, takes Derek's advice and lies when she desperately needs an extension on a school assignment. Soon she is trapped in a web of deceit and the harder she tries to extricate herself, the worse it gets.
Lizzie's soccer coach asks Casey out which creates a problem for Lizzie because she has a crush on him herself. Derek is glad Casey isn't going to be around the house so much, until he has a crisis of conscience after finding out that Scott is also hitting on the older sisters of Lizzie's teammates.
To pay Derek back for his many practical jokes, Casey pulls a huge prank of her own: stealing the office furniture from the new uptight Vice Principal. Everyone assumes Derek did it. The only two people who know he didn't are Casey and Derek.
While Casey is freaking out about her upcoming dance competition and Derek is freaking out (by being annoying) about his upcoming hockey playoffs, Lizzie and Edwin decide they're sick of being the ever-accommodating middle-kids.
Derek bets Casey that she's too much of a goody goody to go out with cool-guy Trevor. Casey desperately wants to win the bet, and changes her image completely in order to attract Trevor. When it looks like she's going to be successful, Derek dares her to go double or nothing.
