At the beginning of Season 1, Sydney is an obvious "daddy's girl," as she openly prefers spending time with her father, Joel Graham because he is a stay-at-home dad. Her mother, Julia Braverman-Graham, is a corporate lawyer, so she doesn't have as much time to be at home. Because of this, Sydney and Julia do not have a very close relationship initially, despite Julia's efforts to be a good mom.
During Season 2, it is revealed that Sydney is academically gifted, much to Joel and Julia's delight. Since Sydney is an only child, Joel and Julia are able to pay more attention to her needs. Julia and Sydney also get closer when Julia realizes she must focus more on her family.
In Season 3, Julia and Joel realize that they may have spoiled Sydney because Sydney is a sore loser every time she doesn't win a game during family game night. Joel and Julia decide to discipline Sydney more, and they receive a negative reaction from Sydney in return. Eventually, Sydney comes around.
Julia and Joel try to have another baby, but turn to adoption when Julia learns that it is very difficult for her to get pregnant. At the end of Season 3, she gets an older brother named Victor Graham, who Julia and Joel adopt.
Throughout much of season 4, Sydney is not fond of Victor and frequently throws tantrums when he gets away with doing things that she was never allowed to do, such as eating while watching TV. Sydney and Victor do not get along like brother and sister, and the last string is pulled, when Sydney confronts Victor about his "real mom". Sydney taunts Victor and finally tells him that his real mom does not love him, causing Victor to throw a metal bat at her head but misses her and shatter the kitchen window.
In the season 4 finale, Sydney takes the first step to accepting Victor as her brother when he asks her to come to the adoption ceremony to which she agrees.
In Season 5, when Sydney receives the bad news of Joel and Julia's separation, she misses her dad. When she and Victor spend the weekend at Joel's new apartment, she hates it. Throughout the season, Sydney constantly refuses to go to Joel's apartment and would rather just stay home. She also blames Victor for their parents' separation, which he takes seriously.
Joel and Julia's separation begins to take a real toll on Sydney when she begins bullying an overweight girl named Melody at school. When her parents confront her about it, she denies it and refuses to talk about it. However, she later breaks down, saying she just wants her dad to come back home. She and Victor are overjoyed when Joel and Julia get back together.
In the series finale, her parents adopt Victor's baby sister, and she is shown being very accepting of it. In the flash forward, Sydney is shown celebrating Christmas with her brothers and sister.