Margaret Cox is a fortune teller, and a background character in The Room Two and The Room Three. She makes her first appearance in The Room Two, as the owner of apartment E7 on 17 Franklin Court, London, where The Séance is held. Information on her can be found in two letters and a newspaper article of that level.
In The Room Two
Maggy makes her debut in The Room Two, Chapter Four - The Séance. By reading the letters of this level, the player learns that Maggy is a fortune teller specializing in Tarot card reading and seances. She works out of her apartment on 17 Franklin Ct. At the time of the player's arrival, ca. 1883, Maggy has been contacted by Robert Bailey, the son of a shipping lawyer. Robert's mother has begun visiting Maggy frequently after the mysterious disappearance of her other son, and Robert sees Maggy as a leech who is taking advantage of their mother's grief. He has threatened to report Maggy as a charlatan to the newspapers.
In order to dodge the press, Maggy writes to her old mentor, Simon Grayson, a.k.a. The Great Khan. She tells him that she knows he has been using a Null artifact as part of his act, and that he "owes" her. Presumably, with Simon's help, she made use of the Null during her own act to increase her credibility to the press.
In The Room Three
When the player is exploring the Grey Holm library in The Room Three, they come across the "Mystical Maggie" machine, a fortune telling booth with an automaton inside. When tokens are placed into the machine, the automaton will display the player's possible fates and give them items needed to find the Craftsman's game-changing artefacts.
Secret letters left by The Craftsman reveal that, in fact, he has trapped Maggy's soul inside the machine after she tampered with the Null. Maggy attempts to communicate with and aid the Protagonist by leaving messages written on the glass of the machine and using the Tarot cards to warn of certain endings. When The Craftsman discovers that she has been interfering, he creates more and more wards on the machine to keep her trapped inside. Despite his efforts, she continues to guide the player until they must remove the Null artifact powering her machine, which shuts her down.
Judging by pages left by The Craftsman, Maggy was likely one of his "apprentices". While it is still unknown exactly how they met, it is possible that Maggy has some relationship to The Craftsman's family, as she has a number of paintings of a castle somewhat resembling Grey Holm hanging in her apartment.
The Craftsman looks down on Maggy and her fortune telling, believing her to be no more than a charlatan. However, he expresses a certain discomfort with her, as she alone of all his apprentices could see straight through his lies. For this reason, he imprisoned her soul and later reinforced it to try to keep her quiet. No matter what he did, however, Maggy was able to reach out, proving to be more powerful than The Craftsman anticipated.
"This pressman isn't going to leave me alone, and you owe me you sow. Since when can you resist putting on a performance? We'll be pioneers." - Margaret Cox
Despite being his apprentice of sorts, Maggy's attitude towards Grayson is catty and somewhat condescending. In her letter to him in The Room Two, she tells him he could never fool her, and expresses her entitlement to the Null based on Grayson "owing" her something. She purports to know Grayson's character and his wants very well.
Maggy's relationship to Robert Bailey is an antagonistic one. The animosity began when Bailey's mother came to Maggy seeking closure on the disappearance of her other son. When their visits became more frequent, Robert Bailey accused Maggy of being a leech and a fraud, and warned her to stay away from his mother lest he expose her as one. He later sent the press to hound her, prompting her to reach out to Simon Grayson for help in putting on a more convincing act.
AS and Maggy were apparently acquainted, as he can be seen in two photographs found in Maggy's apartment. The first is a group photograph showing a séance that AS and Maggy were both a part of. The second is a torn and scratched photograph found framed in her cabinet. AS himself is also the subject of The Room Two's séance. The protagonist receives his messages through Maggy's typewriter and the tarot-reading machine on the table. It is unknown under what circumstances Maggy comes to know him or his spirit, especially considering the events of The Room Two may be illusory and not true to life.
Despite the protagonist visiting Maggy's apartment in The Room Two, the two do not actually meet "face-to-face" until The Room Three, when the protagonist encounters her fortune-telling booth in the Grey Holm library. When the protagonist begins to interact with the machine, Maggy is able to project some of her will through it and guide them towards finding the truth of The Craftsman's deceit. She leaves them messages by writing on the inside of the glass, tipping them off to their next location. She also displays the tarot cards which represent the different paths the protagonist could take at the end of the game.
As the protagonist collects more tokens for the booth and learns of more endings, The Craftsman puts more and more wards on the machine in an attempt to keep Maggy quiet. Despite this, she continues to help the protagonist until they must remove the Null artifact which is powering the booth. At this point, the automaton inside shuts down. It is not yet known for certain what happens to Maggy's soul when the power source is removed. However, it can be assumed that her soul resides within the artifact itself, and is taken with the protagonist to be used in the last level of the game.
- As a spirit medium, Maggy goes by her full name, Miss Margaret Cox. The name "Mystical Maggie" is given to her by The Craftsman when he imprisons her in the Tarot machine, and she never uses it to refer to herself. Additionally, she spells her own name "Maggy", suggesting that The Craftsman misspelled it purposefully. The name "Mystical Maggie", then, appears to be just another way for The Craftsman to ridicule Maggy and her profession.