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 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.

Meredith has only appeared in Season 1.

Trivia

 * 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.