In The GameEdit
Mary is first heard if Bigby decides to check Crane's apartment first during the hunt to find his witch. While there, he listens to a message left by Mary, asking Crane to pay the money he owes the Crooked Man by Friday. He may not hear the message at all as you do not need to click on the answering machine to progress.
She makes her first appearance at the alley of the Pudding & Pie along with the shotgun-wielding Tweedles after Bigby and Snow arrest Crane and are cornered by unmarked cars. As Mary and the Tweedles exit the cars, she introduces herself and demands that Bigby hands over Crane. After the sheriff refuses to do so, she orders the twins to fire their shotguns at Bigby. Mary watches from the street as Bigby transforms into his werewolf form and brutally pummels both of the Tweedles. She tempts Bigby into throwing Dee at her, at which he can be thrown at her or the Jazz Lounge sign, though Mary will duck effortlessly dodging the thrown Tweedle if Bigby throws Dee at her. After Bigby either spares or killes Dum, Mary takes advantage of the distraction and shoots Bigby with a silver bullet. The wound effectively incapacitates Bigby, causing him to fall down, stunned.
As Mary is about to finish Bigby off with the Woodsman's axe, Snow calls out and offers to hand over Crane to Mary in exchange for her sparing Bigby. After receiving the Crooked Man's blessing, she agrees to the deal, but violently steps on and breaks the sheriff's arm and states that they'll be in touch before leaving.
While unconscious after the fight in the alley, Bigby has a nightmare of Mary showing up in his apartment and attacking him with the axe. He then violently wakes up to find himself being operated on by Swineheart, who informs him that Mary's silver bullet nearly killed him and that another similar wound would likely finish the job.
Later, while meeting with Beauty and Beast, Beast tells Bigby that one time, when Beast was getting his payment for his work at a butcher shop, the one who showed up to pay him was Bloody Mary. Later, when Bigby visits the shop, Johann informs him that the Crooked Man's crew -- consisting of the Jersey Devil, Mary and the Tweedles took over the shop from him a long time ago, after they threatened his life. Bigby then discovers the purpose they were using it for in a back room: producing black market glamours and magic with slave labor. He can see a list of clients on a chalkboard if he goes to the shop first (though if he goes to it second after visiting The Lucky Pawn, then the chalkboard will be erased, and Bigby won't be able to deduce as much).
After Bigby returns to the Business Office and the Magic Mirror is repaired, Snow asks him about Crane's whereabouts. The Mirror shows Mary ordering him to Paris until he is needed by the Crooked Man, threatening to deal with him in her own way if he slips up. She then notices that the Mirror is being used to spy on her, and uses her power to break off its vision. Also, Bufkin had to spend more time attaching the broken-off mirror shard to the broken mirror; this is because Mary, who has a terrible influence on mirrors, had physically held onto the shard.
As Bigby refuses the Crooked Man's deal in the Crooked Lair, Mary comes out of a mirror in the lair and decks him after Georgie disorients him by striking him with a chair. She then escorts the Crooked Man through the portal in the window and into his limo. Bigby gives chase after stabbing Georgie and abandoning Jersey Devil and the Tweedle(s).
Eventually Bigby will have to either chase down Georgie/Vivian (the former revealed to be the killer), or chase down the Crooked Man and Mary (the latter driving the limo). In the former case, Mary evades Bigby. In the latter case, Mary quickly shakes him off and runs him over, knocking him unconscious for a time and causing him to arrive at the Pudding & Pie after Vivian's suicide.
Mary later is confronted by Bigby in the Metalworks, the Crooked Man's secondary lair where he produces silver bullets. As Bigby enters the building and searches it, Mary taunts him, but she cannot be seen. When Bigby enters the workshop area when the Crooked Man has his silver bullets molded, she appears behind him and attacks him. The two have a short fight, in which both Fables land blows on the other. Mary flees into the main area of the steelworks, Bigby following her. Her true form is soon revealed as she dashes about the open factory room, slashing Bigby several times before he taunts her, afterwhich she comes out in the open. After more fighting, she creates numerous mirrored copies of herself, which assault Bigby. Though he fights many of them off, he is overwhelmed and pinned down, with Mary and her copies shredding his chest. Bigby transforms into his full form, however, and breaks free, beginning crushing the copies, killing many of them with his wind-gusting breath. The last Mary attempts to stab him in the eye with a large glass shard, but is crushed in his jaws, finally dead.