Mac is 19, a Sagittarius and her hometown is Neptune, California. In the episode where Mac is introduced, she helps Veronica find out who has stolen her password and has created a false score under her name on a purity test that had become a brief fad at Neptune High. Mac, although a friend of Veronica's, is the person who created the test in the first place, thus making it possible for the "sex-crazed 09ers" to access other people's purity tests--and thus is also responsible for the chaos which ensues.
Like Veronica, Mac uses an Apple PowerBook and later a MacBook Pro. Mac vehemently defends the Mac OS X operating system in an argument with an Ubuntu fan. (Weapons of Class Destruction)
Mac has always felt like an outsider in her family, having completely different tastes and views to them. While digging for dirt on Mac's parents, Veronica discovers that Mac was switched at birth with Madison Sinclair. Since the mistake was uncovered four years after the births, the parents decided to keep the children. Each family received a handsome cash settlement from the hospital. While Madison's family invested and flourished, Mac's started a business and went bankrupt. Interestingly, Mac's biological mother shows some longing to know Mac, while Madison's biological family have no interest in her whatsoever.
She formerly dated Cassidy Casablancas, but the relationship ends when Cassidy balks at becoming sexually intimate with Mac. They are back together in time for prom, though. However, Veronica discovers that Cassidy had been responsible for (among other things) the bus crash. Cassidy, intercepting Veronica's warning message, robs and abandons Mac while she is in the shower, leaving her without clothes. He then attempts to kill Veronica, and, later that night, commits suicide. (Not Pictured)
Mac attends Hearst College along with Veronica, and she initially is uncomfortable with male attention. A series of rapes on campus bring up bad memories, but she is eventually able to move on and have successful relationships. Though she at first feels uncomfortable with her new roommate, Parker Lee, Parker's rape helps Mac to see the other girl as vulnerable. When Parker's parents come to take her home, Mac tells her that she should stay and promises to 'have her back.' It is thanks to Mac that Parker and Logan hook up after the Valentine's Day scavenger hunt.
At Hearst, Mac falls for and dates an animal-rights activist named Bronson Pope, to whom she loses her virginity. They date for while until Mac meets Max, a student who sells copies of exams. After the two connect, Mac breaks up with Bronson and begins dating Max.
When Veronica returns to Neptune, she and Wallace come by her house to greet her. She comes to the reunion with Veronica and Wallace. When Madison plays Veronica's college sex tape, she runs to Veronica and Logan to warn them of Madison's mean-spirited prank. Logan attacks their classmates and Veronica tells Mac to head for an exit before she turns the sprinklers on. Mac sends links to Veronica on the case and updates on viral videos of Logan and Carrie Bishop. In the end, Mac quits her job at Kane Software and goes to work with Veronica at Mars Investigations.
After the events of the second book, Mac took a leave from Mars Investigations and went on a vacation to Istanbul.
- Each season, Mac features different highlights in her hair: Season 1, blue; Season 2, red; and Season 3, yellow-blonde.
- She's a vegan according to her mother. (Silence of the Lamb)
- She has a preference for organic foods (The Thousand Dollar Tan Line)
- Veronica Mars
- Season One
- Season Two
- Season Three
Majorino filmed scenes for 3x04 Charlie Don't Surf, but they were deleted. In the scenes, Mac is in Wallace's class and is visibly uncomfortable with one of the students in the class. While studying together, Wallace puts his arm around her, and she stiffens, telling him "It's not you." Later, Wallace confronts the student from their class, only to discover that the boy's interest in Mac is platonic, wanting to reunite with her as they used to go to computer camp together. In the final scene, Mac references that another student from her Comm class makes her uncomfortable. Wallace quietly realizes that all of these events are due to the aftermath of her relationship with Cassidy Casablancas.