Meredith Sorenson

Meredith Sorenson was Byron's student with whom he had an affair. Aria and Alison know about the affair at the start of the show. After Byron's sabbatical, Meredith returns to Springfield seeking Byron once more.

Season 1
One day, Aria and Alison discover Aria's father kissing Meredith in a car. Alison pushes Aria to tell her mother, but Aria listens to her father, who forces Aria to keep the affair a secret. Meredith becomes friends with Ella, while Ella thinks Meredith is sweet and kind before she hears the truth. On the day that Aria is ready to reveal the affair to her mother a year later, Ella receives a note already informing her of the affair.

Meredith was Byron's teaching assistant, and she reappears in the Montgomery's life when she seeks out Byron again, ostensibly seeking "a recommendation." She has the audacity to introduce herself to Aria and Ella, smiling all the while. She even befriends an unsuspecting Ella, who resents her own behavior later when she discovers her mistake. Aria is outraged that her father would repeat his mistake, but Byron says that he cannot avoid her, as they work in the same institution, Hollis College...

Season 2
In "The First Secret," Aria visits her father's office at Hollis College. She is about to leave a note for her father, when she sees Meredith lying barefoot on the couch of her father's office, lazily reading a book. Aria is not very suspicious, though she finds the woman's behavior odd. When Byron returns to his office, he expresses his surprise at seeing Meredith there, but acts coolly. Aria attributes Meredith's presence in his office to her father being so cool in the eyes of his students.

In this same episode, the footage of Aria discovering her father's affair is replayed, meaning that the precise date was just before Halloween 2008. When Aria returns home, Byron lets Aria know that he had tried to call her numerous times, obviously trying to prevent Aria from ratting out his affair. He announces that Meredith is dropping his class, implying that their relationship is ending.

Season 3
Meredith appears, once again, in the second episode of the season, Blood is The New Black, where she goes for a job interview at the same school as the Liars. It is later revealed that Aria and Alison went back to the office of Byron to try to find evidence about whether Meredith and Byron were still together. An earring is then found, leading Aria to become shocked and upset, and Alison to then suggest they trash the office, and making her father think it was Meredith's work.

In the present, Aria admits to Byron that it was really her and Alison that trashed his office. This leads to Byron telling Aria meet up with Meredith and apologize. While Aria and Meredith are talking, Aria hands the earring to her, explaining that she found it underneath her father's couch cushions in his office. However, Meredith tells Aria that the earring does not belong to her.

In "Stolen Kisses," Byron tells Aria that Meredith got the teaching job at Rosewood High, which unsettles Aria.

Book - TV Show Comparision

 * Meredith's character in The Pretty Little Liars book series goes by "Meredith Gates," rather than Meredith Sorenson. For some reason, the television series producers chose to change the character's last name, similar to the shift from Lucas Beattie in the books to Lucas Gottesman on television.
 * Meredith left for a while and never was sexual with Byron in the show, but in the books, she was pregnant with his baby.