Season 6Isabella first appeared in the episode, Can't Hardly Wait, when Mia took her along with her meeting with Darcy Edwards and Manny Santos. The fact that she was Mia's child caused a controversy with Darcy, a Christian, who would not let Mia join the Spirit Squad due to Mia being a teen mom. She's said to be a fan of PJ J.T., a children's television character played by J.T. Yorke. She is shown to grow close with J.T. until his death. She is seen playing with him at a park in a memorial video shown in The Bitterest Pill.
Season 7In the episode, Sweet Child O' Mine, for Isabella's birthday, Lucas shows up and brings a kid's motor bike, which Isabella is shown to love. It is in this episode that it's revealed that Isabella doesn't know he is her father due to Mia's choice to rather tell her when she is older. Afterwards Lucas promises to be more responsible and says that he has grown up now then when he originally left. Mia puts her trust in him and they start dating.
Mia drinks and Johnny DiMarco asks her when she last checked on the little tater tot. Mia goes to Jane's room and finds that Isabella is missing. She cries out if anyone has seen her. She turns around and sees that Jane is holding Isabella and that she is scared. Jane tells Mia to leave before it's too late. Mia takes Jane's advice and attempts to leave. As she is about to walk out the door, the police show up and orders everybody out. The female police officer asks Lucas if Isabella is his child, and Lucas denies it, stating that Isabella is Mia's child. The officer calls in Children's Aid despite Mia's pleas as she holds her daughter to her. At the end of the episode, Mia and her mother are seen at Child's Aid. Mia promises to put Isabella first and says that the father was not involved. In a deleted scene, Mia and Jane make amends and Mia apolgizes for not believing Jane about Lucas. She hugs Mia and also promises to be a better aunt towards Isabella.
Season 8In Uptown Girl (1), Mia is going to Power Squad try-outs while holding Isabella, and she starts acting up, saying she wants a cookie.
In Uptown Girl (2), when practicing for her modelling job, Mia introduces Isabella as her sister, as if she is embarrassed by her. She later slept with Tom Blake to get the job as the T-Bombs girl, knowing she has a daughter, Isabella, but Mia really wanted the job.
In Jane Says (1), she is seen over at Jane's house eating dinner with their family (including her father, Lucas). Jane's father gets very close to her, which scares Jane. Lucas tells his father that no one ever wants to see him again, because of his sister's molestation and in fear for Isabella.
In Up Where We Belong, she is now taking ballet classes. When her mother drops out of school, Isabella is seen comforting Mia when she was crying and asks her if she had a boo boo. However, Mia said "No, sweetie. Mommy just loves you so much."
In Just Can't Get Enough, Izzy is seen with Mia and her grandmother. She tells Peter that he looks sick. Mia later leaves for Paris, France for her modeling career and finishes the semester with tutoring. Isabella joins her mom and her grandmother to go to Paris.
- Isabella's 3rd birthday took place in the April 2008 episode, Sweet Child O' Mine.
- Isabella makes an appearance in the season 7 opening credits in a sequence with Nina Dobrev and Charlotte Arnold. However, she is uncredited.
- Isabella is the second child of teen parents to not be adopted or aborted. The first was Emma Nelson and the third was Rock Dallas.
- Isabella's favorite show was PJ J.T.
- In Behind The Scenes videos, which can be found on YouTube, it shown that Isabella was supposed to be younger than the actress who played her, with a set of infant twins supposed to play the role. However, Nina Dobrev wasn't able to film the scenes without either baby crying. Instead, the writers had Larissa fill the role.