|“||Now you know what it's like to really be afraid. The way you made us feel. Say goodnight to the world, bully.||”|
The relationship between Mona and Charlotte was always a negative one, even when they didn't really know each other. Charlotte, as "CeCe Drake", manipulated and fed Alison DiLaurentis ideas on how to bully Mona throughout High School. She even helped Alison name Mona, "Loser Mona". After Alison went missing, Mona started stalking Alison's former friends under the alias of "A". After she was caught and admitted to Radley Sanitarium, she befriended Charlotte (who she originally mistook as Alison) and told her all about the game and the girls. Charlotte made a deal with Mona: Mona would help her get out of Radley, and in return, Charlotte would play the game with her. Charlotte became addicted to the game, and stole it from Mona to become a much more vicious A. Later, Mona attempted to get close to "A" to figure out her identity, and the pair planned a fake murder that would result in Alison being arrested. Mona planned to sabotage the deal by turning on A, but Charlotte found out and viciously attacked her over Thanksgiving break. Charlotte kidnapped her, put her in The Dollhouse, forced her to pretend to be Alison (dress, talk, and act like Alison), and tortured Mona when she didn't do as Charlotte wanted. After Mona escaped and Charlotte was revealed to be A, Mona continued to be haunted by the events and had nightmares for many years. Five-years-later, Mona returned to Rosewood for Charlotte's hearing, and told the judge to let her out and that she sympathized with her. Charlotte was found dead after her release, and months later, Mona confessed to having killed Charlotte in self-defense.
A recently caught Mona is admitted to Radley Sanitarium to receive heavy treatment. At her room in Radley, a nurse opens her door and a woman in a red coat appears in front of Mona. Mona looks up at her and eerily states that she did everything the woman asked her to.
The Liars recruit Mona's help in figuring out of Alison is really A, to which Mona reluctantly agrees to. She starts digging into Alison's past, trying to figure out what would have made her kill Bethany Young, and the truth about her past.
On Thanksgiving day, Mona helps her mother carry out her bags and promises to follow her later as she has things to do first, and when she is walking back to the door, a blonde figure in a black hood is seen watching Mona. Mona doesn't see the figure but is spooked, so she hurries inside and locks the door and goes upstairs. She calls Ari to inform her that she believes that Alison is "A" and that she can prove it. While she talks to Aria the same figure (presumably A), picks the lock on the front door. The figure enters and lowers a black hood to reveal long blonde hair, and walks softly up the stairs to Mona's room. The figure enters Mona's room, and a shocked Mona gasps when she sees the woman. A loud scream is the last thing that is heard.
Later in the day, the Liars arrive at Mona's house to find the house wrecked and blood everywhere. When Hanna runs upstairs, she finds more blood and signs of a struggle. The police arrive and declare that the amount of blood in the house indicates a murder and that Mona Vanderwaal had been murdered. That night, A approaches the Fields house and switches out baby Jesus for a Mona doll. She opens the trunk of her car and sets Jesus on top of Mona's pale, unmoving body, before closing the trunk door firmly.
A month has passed since Thanksgiving, and Christmas is around the corner. Mona's body is still missing, and the police are still investigating her disappearance and possible murder.
At Alison's Christmas party, "CeCe Drake" returns from France she was hiding from the police. She visits Alison, and the two start talking about Mona. Alison admits to having had a dream about her mother, who warned her about Mona, and CeCe quickly says that she shouldn't worry about Mona as she can't hurt her anymore.
In a flashback, Mike explains that a few nights before Thanksgiving, he went to Mona’s house to surprise her, but found her draining her blood. Mona told Mike that she has been offered a chance to make things right by exposing "A" and bringing them down once and for all. Mona elaborates that she is going to smear the house with her blood and make Alison look responsible for her death since "A" wants to see Alison arrested. Mona says that even though she hasn’t been in direct contact with "A", she will find out who it is after she earns their trust. After she fakes her death, she’ll disappear and find out A’s identity, and once she finds out, she’ll come back, resulting in Alison getting acquitted. Mona admits that all she wants is for the girls to trust her, and for her to be painted as the hero of the story.
In the present day, Mike admits to Aria that he believes that "A" double-crossed Mona and actually killed her and framed Alison for the murder. He reveals to Aria that he visited Alison in jail and told her about Mona’s plan in hopes of finding out if she knew anything about "A".
The Liars are abducted on the way to prison by A, who takes them to their Dollhouse, where they wake up in exact replicas of their room. When the doors open they are reunited and are lead to a living room that looks exactly like the one Alison's House. In the room, a blonde wearing an Alison mask, Ali's yellow top, and clothes identical to those she wore when she went missing, is playing a grand piano. Hanna calls out Alison's name, and the blonde looks over and lowers the mask to reveal to the shock of everyone, a very much alive Mona Vanderwaal. Hanna, relieved to see her best friend alive, realizes that it is Mona and calls her by her name. However, Mona claims that while it's been a long time, she hasn't changed that much, and claims that she is Alison not Mona.
Throughout her interactions with The Liars, Mona is revealed to have been brainwashed and trained by A to know all of A's alarms and sounds. The meanings behind them, the games A likes to play, and how to act. She also remains adamant about her identity of being Alison and not Mona. She also expresses her fear to the girls on what will happen if they don't behave and play along with A's games.
That night, Mona opens up to the Liars and reveals the torture that she's had to endure since she's been kidnapped at Thanksgiving. She states that A blared the sounds of her family crying at her funeral until she couldn't handle it anymore, put her in a hole and withheld food and water for days, and blared the siren until she would rather die than listen to it again. She also admits that A wanted her to be Alison, so that's who she became when A was watching in order to survive.
The next morning, A gifts Mona a gas mask much to her surprise. A note is attached to the mask that says, "Because you're my favorite -A". She looks at the camera and asks if A wants her to put it on, and then does even though she's afraid. After talking to the other Liars, Mona admits to thinking that "A" gave her the gas mask because Alison is their favorite, and Alison’s is the only one "A" wants to keep after the prom.
At prom, Mona helps the Liars lure Charles out of hiding under the false pretenses of celebrating the prom. When Charles is close enough, they use a device that blinds him and tries to make their escape. Mona runs out of the doors and is shocked when she discovers that the entire building is fenced in by an electrical fence, and screams when the doors slam shut behind them. Mona is horrified when she realizes that they are trapped outside of the Dollhouse with nowhere to go.
With Mona and the Liars trapped and forced to witness Charlotte's reveal as A and hear her story, Charlotte mentions that the unconscious Jason and Kenneth weren't dead. They could hear everything going on around them, but couldn't move or speak. A tearful Mona admits that this is the same thing that Charlotte did to her - her brain was telling her to scream but her body couldn't move. She states that Jason and Kenneth are living a nightmare they can't wake up from.
While telling her story to Alison and the trapped Liars, Charlotte then reveals how she took the A-Game from Mona. When Charlotte was forced to return to Radley after that night, her out privileges were removed due to her sneaking out. Charlotte was suddenly alone again, as Jessica had stopped visiting her. Shortly after, Mona was admitted to Radley and Charlotte quickly befriended the, "craziest girl". Mona's doctors had her heavily drugged, which meant that Mona didn't know who she was talking to most of the time. Charlotte would sneak into her room every night for storytime, and due to the resemblance between Charlotte and Alison, Mona was easily manipulated into thinking Charlotte was Alison. In a flashback, Charlotte visited Mona while wearing a red robe, and Mona mistook her for Alison again. Mona stated that she, "did everything she asked her too". Charlotte told her she was proud of her and to keep taking her meds, which Mona agrees to. Charlotte then told Mona to tell her everything she knew about The Liars.
In the present, Charlotte explains that she was upset when the doctors started weaning Mona off her meds since listening to what Mona did to the Liars was the only thing she looked forward to. Ali asks Charlotte if Mona did know it was her all along, but Charlotte claims that she stopped visiting Mona before the doctors took her off the heavy medication. She admits that she knew she could never trust Mona, as she had run over Hanna Marin, her legit friend, with a car which to her, meant no sense of loyalty. Charlotte knew that Mona wasn't ready to end the game, and she had a talent for sneaking in-and-out of places. So, Charlotte made a deal with her - Mona would help her get out of Radley and in exchange, she would play the game with her. She admits that Bethany was right, leaving wasn't the hard part, but she knew she needed Mona's help to stay gone. Charlotte's first assignment was making new friends in Rosewood.
In the present, Charlotte says that Mona told her that the Liars were happy that Alison was gone, which angered her deeply. The Liars were supposed to be her friends, and that everyone got what they deserved. Mona admits to the Liars that didn't remember CeCe visiting her, but someone at Radley had been giving her puzzles and twisted rhymes, which got her excited to play the game again.
Charlotte reveals that the night of the plane crash, she had sent a decoy Red Coat, Sara Harvey, to distract the Liars. Sara was supposed to keep a deceived Mona, who thought she would finally meet A, distracted, while Charlotte trapped the Liars. However, Shana Fring showed upsetting the lodge on fire causing the plan to go awry. In a flashback, Charlotte saw Mona talking to Spencer, Hanna, Emily, and Aria asking them if they saw Ali as well. Mona said that Alison pulled them all out of the fire, but Hanna said that she might be hallucinating. It was because of Mona's thoughts that Charlotte found out that Alison was really alive and had survived that night.
Later, when the rest of the Liars escape A's office and head to Radley to help Alison, Mona stays behind to hear the rest of Charlotte's story as she has to know how the game ends.
Five-years have passed since Charlotte's arrest and being institutionalized, and Alison is petitioning the courts to release her. Mona returns to Rosewood and insists to be heard, despite Alison's legal protests.
In the afternoon, at Veronica Hastings' political rally, Mona approaches Spencer and the two have a brief conversation about their respective careers. When Spencer is about to walk away, Mona asks if she still has nightmares about what Charlotte did to them while she was A. She admits that she still does and that she has been through a number of shrinks and medication, but she still has bad dreams.
At the court, when it is Mona's turn to speak, she originally seems as if she is going to be against Charlotte's release. However, she crumples her speech and instead states that Radley is what twisted Charlotte all up, to begin with. She states that Charlotte deserves a home just like everyone else and that the judge should, "let her out". She then leaves the courtroom visibly upset. Due to Mona and the other Liars' testimonies, Charlotte is released from Welby State Psychiatric Hospital.
The night after her release, Alison reports Charlotte missing, and her body is discovered outside of The Church. While her death is at first ruled a suicide, the police begin to suspect foul play. At Charlotte's funeral, Mona sits in the last pew looking solemn yet serious.
- Both were once leaders of The A-Team.
- Both were members of The A-Team when they weren't in charge. Mona was a member of Charlotte's team and Alex's, while Charlotte temporarily worked with Mona.
- Charlotte stole the A-Game from Mona, which always bothered Mona.
- While in Radley, Mona thought she was speaking to Alison when she was really talking to Charlotte.
- Charlotte kidnapped Mona and faked her death so that she could take her to The Dollhouse.
- Mona was the one to figure out the anagrams that Charlotte left to tell the girls her former name, Charles.
- Charlotte once admitted to never being able to trust Mona.
- Mona killed her in self-defense after failing to blackmail her into giving up the game and leaving the town alone.
- After Charlotte's death, a part of Mona reverted back to her High School persona, as that was a "safe place" in time for her.
Charlotte (to Alison about Mona): I could never trust Mona. She was Hanna's legit friend and she ran her over with a car. Where's the loyalty in that?
Mona: I did everything you asked me to.
Charlotte: I'm proud of you.
Alison: You are?
Charlotte: You're getting better. Just keep taking your meds.
Mona: I will, Ali. I promise.
[Mona and Charlotte in a flashback to Radley]
Charlotte: You brought flowers? Is that why you wanted to see me? To welcome me home with flowers?
Mona: I couldn't give them to you in the hospital. Alison wouldn't let me.
Charlotte: Why did you want to visit me?
Mona: For the same reason you came here. To see if there was anything to worry about. I didn't visit, but I kept an eye on you. I watched for five years. Five years of you making the doctors feel so clever with all the progress you were making. You played them all. The court, the lawyers, your own sister. But you couldn't fool me.
Charlotte: You always were the smart one, Mona, not Spencer.
Mona: Now, you're out, and you think you can start hurting people again? Well, I'm not gonna let that happen.
Charlotte: Who's gonna stop me, is it you?
Charlotte: Do you still see her when you look in the mirror? The, uh, the loser with the pigtails and the frumpy sweater. Because I see her. I see her right now. None of you are sure when you look in the mirror. None of you are really certain who you are. I did that. I took that away from you, the same way everything was stolen from me. And now I'm back. And everything that happened before, that's gonna feel like a picnic.
Mona: I won't let you do that to my friends.
Charlotte: Oh, no one's gonna believe you. Not only did you lose the game, but you lost the story. It's mine, everything is mine.
Mona (while holding her over the edge of the window): People will think you committed suicide your first night home. How tragic. Jump. Jump or I'll push you. I'm giving you more of a chance than you ever gave any of us. Maybe you'll land just right and live. A few broken bones and you get to me send me to prison. It's possible. You're thinking about it. You're thinking about a lot of things right now. Aren't you?
Mona: Listen to me. That taste in your mouth, that's what dying tastes like. Get used to it. Because you're gonna choke on it every day for the rest of your long, miserable life.
Charlotte: I knew you didn't have the guts.
Charlotte (to Mona about the Liars): They will never love you!