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Meredith was a banshee who was tested by psychologists because she has shown the same symptoms (banshee powers) as Lydia's grandmother Lorraine. They nearly killed her. Later she was hospitallised but never truly recovered. After Stiles and Lydia were captured by Brunski in Eichen House he revealed that he killed her grandmother along with other people with mental diseases because in his mind he was helping them.
At some point in her life, she was admitted into Eichen House. In her first appearance, is seen talking on the phone although there is no one on the other end. She proclaimed that they needed to hear the whole story because one of them was standing right behind her and walks around Stiles and Oliver. Stiles then tries to use the payphone but found out that after a suicide at Eichen House the phones are turned off for 24 hours. Meredith later escaped Eichen House and is in Beacon Hills High until Danny points out to the Coach that they have a new "student". She then reveals to the class that she is from Eichen House. Coach then calls them to get her. Kira then tries to take her with her instead in a hope that she could help them find Lydia after she was kidnapped by the Nogitsune. Later on she was found plucking the wire of a piano hearing voices she is then found by Brunski who came to take her back. Coach Finstock then tasers Brunski and Scott,Kira and Stiles takes her to Scott's house. At Scott's house Isaac and Stiles try to get Meredith to find Lydia but Lydia had alrready told her that she doesn't want to be found. Isaac and Stiles then realizes that she is a banshee like Lydia and tries to get her to use her power. She then hears Stiles' phone ring but isn't actually ringing Stiles then gives her the phone and tells them that the person on the phone told her something in french.
Lydia and Stiles go to Meredith for help with deciphering the second deadpool key. Meredith claims she can't help, but ends up giving Lydia a phone number that partially spells out Aiden's name. She almost has a breakdown, though, and Parrish takes her back to Eichen House. Lydia and Stiles go to her again for the third cipher key, but she complains that she can't help them. They press her, but she says she can't. She starts to freak out, and Parrish puts a stop to the questioning before they get any answers.
Later, Meredith is shown on the floor of her room with a bed sheet tied around her neck, apparently dead of suicide.
Later, It is revealed that she faked her death when Brunski tells Lydia, Stiles, and Parrish as he's dying that he isn't the Benefactor and he wasn't controlling Meredith like they thought. Instead, Meredith was controlling him. Meredith then walks out into the basement and reveals herself as more calm and composed than any time previous. She says that Brunski wasn't on her list but he was a bad man-revealing that she's the Benefactor, and the one behind the assassinations and the one who hired the assassins including The Mute and Garrett. After the Hale Arson, Meredith was hospitalized in 2009 and even shared a room with Peter Hale, who was in a coma after the Hale. it is later revealed that she only overheard Peter's insane rantings while he was hospitalized after the fire. He fantasized about killing all the supernaturals in town and starting over and using the Hale fortune to do it. Meredith simply helped carry out his wishes.