<Li> Chad Lowe portrays Byron Montgomery, the father of Aria and Mike, as well as the husband of Ella . He is the center of one of the first story lines due to him having an affair with one of his students at Hollis causing all sorts of issues with his family . Due to this, him and Ella get a divorced but later remarry in season 6 with Aria as their officiator . Chad Lowe was the first cast member to direct an episode of Pretty Little Liars, followed by Troian Bellisario . </Li> <Li> Shay Mitchell portrays Emily Fields, one of the five Liars . Emily is the sporty one in the group . She is the best swimmer on the high school swim team, and eventually becomes a coach of the team . Emily's demeanor is kindhearted and very loyal to those she loves . Emily is a shy closeted lesbian in the beginning of the series, in love with Alison DiLaurentis . Over the course of the series, Emily came out to her parents that she was in a relationship with Maya St. Germain . After Maya's murder, Emily develops a relationship with Paige McCullers in season 3 . They're together for a while, until Paige betrays Emily's trust . After the time jump, Emily has dropped out of the university she attended in California after the death of her father and she came back to Rosewood with a secret . She ends up donating her eggs in season 6 to help to start a family . As of The Darkest Knight she is now working at Rosewood High School as the swim coach . In Season 7, it is revealed that Alison is pregnant with Emily's baby after A.D stole Emily's eggs after she donated them and impregnated Alison while she was in Welby . Emily confronts Ali about the baby and she agrees to have it for her . Soon after, Alison confesses her feelings for Emily and the 2 enter a relationship . In the series finale, Emily and Ali are raising twin girls, Lily and Grace . Alison proposes to Emily who accepts . </Li> <Li> Nia Peeples portrays Pam Fields, the mother of Emily as well as being the wife of Wayne . </Li> <Li> Sasha Pieterse portrays Alison DiLaurentis, one of the five Liars and the former "Queen Bee" of her clique, and the most popular girl in school before her disappearance . She enjoys using people's deepest secrets against them to keep them in line . Charming and manipulative, Alison managed to manipulate all four of her friends in one way or another and is skilled at finding ways to blackmail others . It was later revealed that Alison is alive and was on the run from "A". After the five - year time jump, Alison marries a man posing as Dr. Elliott Rollins, who was her sister Charlotte's psychiatrist . In the beginning of Season 7, Alison finds out that he is not the "good" man that she thought she married and with the help of the other girls, they manage to kill him before he kills them . Alison is now an English teacher at Rosewood High . It is also revealed in season 7 that she is pregnant with Emily's baby . Shortly after, she admits to being in love with Emily and enters a relationship with her and intends to raise the baby with her.In the series finale, she is raising twin girls, Lily and Grace, later on in the episode she proposes to Emily . </Li>

What is the theme of pretty little liars book 1