Casey and Derek both had great lives before they met each other, as well as single parents. When Casey's mom, Nora, meets Derek's dad, George, they date, and ultimately marry each other, causing Casey to have to move into Derek's house, losing her friends and old school. Now, Casey and her sister, Lizzie, must deal with a new house, a new school, two new step brothers, Edwin and Derek, a new step sister, Marti, and a new step father, George.
Casey, at first, feels angry at her mom's decision, and hates the fact that she must share a room with Lizzie, with almost no space, and her having no say-in on what the family does, since it's still not really her house. But Casey soon grows accustom to her new house, but still can't stand Derek, her obnoxious, egotistic new step brother, whom, like Casey, is also the eldest of their siblings, which causes a reoccurring conflict between the two, who are used to bossing around their siblings.
Since the beginning, Casey has made a good friend, Emily,is going out with max, the football's team quarterback . Casey is really fitting in and starting to enjoy her new life, but she may never get used to Derek.
Final: 4x18 -- Futuritis (Mar/25/2009) [Special Airtime: 05:30 pm]
As graduation day approaches, a worried Casey is having difficulty writing her valedictorian speech, which she blames on her fear of Derek pulling a prank and ruining it until Derek points out that she's actually afraid of what the future holds. Meanwhile, Edwin is concerned that he won't be able to live up to Derek's reputation at J.S. Thompson High when he goes there in the fall. The family celebrates Casey and Derek's high school graduation and the two make a very awkward announcement: that they are going to the same university.