How The AD Reveal Should Have Gone (Alex's Backstory)
When Alex left her adopted home, she begged/borrowed/stealed/etc enough money to get to the states in order to find her real parents. During this time, she met Wren, and he became infatuated with her. This was 2 years before Ali disappeared.
Alex, at first, thought Jessica was Mary. She visited the DiLaurentis household and explained who she was and the horrible life she had endured. Jessica played the part of Mary, internally freaking out about the amount of chaos Alex’s reveal would undoubtedly cause. She put Alex up in a hotel room while she asked her to be patient as she got up the nerve to explain to her family about Alex’s existence.
At this point, Alex was not aware that she was a twin, let alone that her twin lived next door to her “Mom”.
Jessica immediately went to Peter, and the two of them devised a plan. Jessica would use her authority on the board at Radley to commit Alex as someone with multiple personality. Peter, being genetically related, signed Alex in as “Bethany Young”. They used Alex’s true back story (one which Alex originally had no problem agreeing to) as proof that she had a mental break, complete with accent.
Once Alex/Bethany was in Radley, Jessica kept tabs on her, and after the mind numbing drugs kicked in, would occasionally take Alex/Bethany on outtings. This is when she would insist Alex call her “Aunt Jessica”. This was also why Jessica had told Ali you can “never turn your back on a Hastings”, because she was well aware that she could never share her knowledge of Alex’s existence, and if Ali had ever seen Alex, she would think she was Spencer.
There were a few times that Alex/Bethany was able to escape.
(photo credit to PLL Theories)
The first time was Ian’s Halloween party. While there, she overheard Noel talk about his and Ali’s plan to scare the girls. At this point, she hadn’t yet seen Spencer. Alex had fuly intended to severely hurt/kill Ali in that abandoned house, though Ali was stronger that she thought. Once the girls were freed from the locked room, Alex finally saw Spencer and she seethed with rage. She realized the true reason behind Jessica betraying her, and instead of leaving town, as she had originally planned, she opted to go back to Radley and devise a new plan.
Before she did, she befriended Ian, who was a member of the NAT club. At that point, she both flirted with Ian, as well as paid him with money provided by Wren, and convinced him to film Alison and her friends. He didn’t understand why “Spencer” wanted to be filmed, though Alex incorporated it as part of her flirting, telling Ian she wanted to see how Ian saw her in his eyes.
Alex’s first priority, however, was still hurting Ali. Alex/Bethany would never forgive Jessica for having her wrongly commited. She starts writing to Ali, although when Ali visits Radley to see her, Alex has her roommate(Kimberly Brown) pretend to be “Bethany”. Ali, being the mean girl she was at the time, enjoys playing with her new toy.
When Ali begins to get “A” messages (from Mona), she begins to wonder if it isn’t Bethany sending them. She antagonizes Alex/Bethany through letters and “visits”, making things even worse than the already are. At the same time, Ali isn’t completely certain that “Bethany” is behind the threats, so after receiving the lipstick note on the mirror, she devies a plan to either expose Bethany or have her take her place.
Ali drops of an exact duplicate of her outfit at Radley, with a note for Bethany to escape and come meet her so they can finally work things out. Ali figures she and Bethany can either hash things out for good, or that if someone is trying to kill her, having Bethany run around dressed as she is hedges her bets a little bit in case it is someone else threatening her.
At this point, Alison believes that the other Liars are innocent, and not the ones leaving messages. That said, she can not have them in her way for all that is about to go down that night. So, she drugs them.
Meanwhile, Jessica receives a phone call that Alex/Bethany has escaped. She freaks out, and forbids Alison from leaving the house at all.
Spencer and Ali argue. Ali walks back towards her house and Spencer walks towards the woods/house. Melissa hears heard the argument between Ali and Spencer, as do the girls (Aria, Hanna, and Emily), in a drug induced haze. The girls arrive in the bushes in time to see someone dressed like Ali, hit Alison. Mrs. D also sees Alex hit Ali from the window. Mrs. D rushes from the house as Alex runs away. The girls, again drugged, begin to chase Ali’s assailant.
Mrs. D, believing Ali dead, buries her. Mrs. Grunwald pulls Ali from the grave. The girls, chasing Alex through the woods, finally lap back around to the gazebo area and attack Alex. As they begin to attack her, they start to hallucinate that it is Alison, and finally stop. They leave Alex’s lifelss body in the gazebo area, and Melissa stumbles across it. Seeing only the clothes and hair, Melissa thinks Spencer killed Ali, and buries her to hide the evidence.
At this point, Alex’s roommate, Kimberly Brown, who had escaped from Radley with Alex, leaves their meeting spot and comes looking for Alex to figure out what is taking so long. She sees Melissa burying Alex, and as soon as Melissa leaves, she digs out the grave and saves Alex.
As it turns out, this was the worst mistake Kimberly could have made. Alex, now set on burning down everything to do with Spencer, and the other liars, kills Kimberly Brown on the spot, switches clothes with her, and buries Kimberly in the grave. That way, when her body is found, no one will expect she is alive and able to exact revenge. At this point, Alex still believes she has killed Alison.
Mona sees Ali walking along the road, sends her out of town. Ali knows for sure that someone is out to kill her, and that her Mom buried her without hesitation. There is no reason to stay.
Alex then spends the next year devising a plan to get revenge on the liars for trying to kill her. She enlists Wren to start dating Melissa, to get his way into the Hastings trust, and to learn more about Spencer. As it turns out, Wren starts falling for Spencer, which only makes Alex hate Spencer more.
She starts communicating (electronically) with Mona, Lucas, and Jenna, who she learned from the NAT tapes had hated Ali as much as she did, as was also picked on by the liars. When Aria returns to Rosewood, Alex gently nudges Mona to start sending A messages to the girls again. She tells Mona that she will be an outcast agin, now that the Liars will be together again. In essence, she sets Mona free on the girls to torture them, knowing at some point she will escalate the game to her own level.
When she notices the DiLaurentis house is sold, and that workers start to dig around the gazebo area, she knows she will need to get ahold of that body to switch around medical records. “Bethany Young” has to remain dead, or Jessica and/or Peter might start searching for her. She pays off some cops and people in the morgue and is able to alter paperwork, and steal the body.
She noticed Jessica and Charlotte together, and eventually figures out how Charlotte fits in to the story. When she first approahces Charlotte, Charlotte does not believe her. She thinks it is Spencer trying to figure out where Ali is, if Ali is alive, and that she still wants to find her and hurt her. Once Alex gains Charlotte’s trust, and Charlotte realizes how awful Ali was to Alex, Charlotte becomes a double agent, though doesn’t immediately tell Alex that Ali is still alive. (Alex is still wondering what happened to Ali’s body)
Alex tries to burn the girls to death in the lodge fire, and that is the night she realizes Ali is still alive. However Ali goes immediately back into hiding. Alex then spends Season 4 trying to find Ali, and using the Liars to do so. It is Alex that kills Mrs. D, and Mary takes the fall for her (as she did for Spencer with Eliot) Once Alex heard thought Mona (via Shana) that the girls found Ali, Alex knew that Mrs. D that had to die, because Alex couldn’t have Mrs. D spilling the secret that Spencer had a twin.
Alex has also realized that Charlotte had been lying to her about Ali, and that is why Charlotte agrees to “take the fall” as Big A- to protect Alex. Season 5 up to Charlotte’s reveal is about laying the groundwork to have Charlotte take the fall with everything wrong done towards the girls. At this point, Alex is mostly done with revenge, and just wants to live her life out with Wren, Mary, and eventually Charlotte (once she is released).
Then Charlotte is killed, and Alex is denied her family. She thinks one of the Liars did it, though doesn’t know which one. She enlists the help of Mary, Eliot (Charlotte’s true love), and Wren to help figure out who killed Charlotte.
Then… Alex starts to fall for Toby. While Alex had never really been jeaous of Spencer’s life before (I mean, who would with Peter as a father?), she did start to covet Toby. There were two problems here- Yvonne and Wren. Alex believed she could deal with Wren, though Yvonne would have to go. Therefore, she set up the car accident, and while Toby was knocked out (and before help arrived) further injured Yvonne so that her injuries were mortal.
Next, she had to convince Wren that she would kill Spencer, and take over her life, allowing her to be with Toby. This met with more resistance than she expected, and she eventually killed Wren, worried that he would tip Spencer off. Alex knows she is playing the long game with this, and uses Aria and Ezra’s wedding (with Toby’s return) as her in to fully take over as Spencer and work toward getting Toby back.
As for Mary, it could go either way as to whether she knew Alex’s ultimate plan to take over as Spencer until the very end. I am going to say that until Spencer was kidnapped, Mary did not know, and by then, it was too late.
