|“||There are people who wanted to hurt her, a man and a woman.||”|
— Seth (about Alison and her potential murderer/s)
Seth is the creepy little boy from the Doll Hospital in Brookhaven. He supplies the Liars with information regarding Alison. There is no way of understanding whether or not he is telling the truth or lying. The audience is told by Martha that he is gifted, meaning he can see the future and things that have not happened yet.
In If These Dolls Could Talk, the Liars travel to Brookhaven, specifically to a doll hospital which they suspect sold a voodoo doll to "A" who then sent it to Alison. While the owner, Martha, is talking to the girls outside the shop, Aria looks into the shop window and sees a little boy blending in with the dolls. As they go inside, Martha (Seth's grandmother) calls for him. As the Liars try to explain to Martha what the doll looked like, Seth comes over and states that they are talking about the voodoo doll and that there was another girl who came to the shop asking about the same one. The girls ask him when she came, and he replies that it was the summer before last (the summer when Alison was killed). Hanna then asks him what the girl who came in was asking. He answers that she wanted to know who had purchased the doll. Emily then takes out her phone, puts up a picture of Alison and shows it to Seth, asking if this was the girl who came in. He looks at it, then replies that that was the girl's face, but her hair was dark, not blonde. This means that Alison had presumably come into the shop as Vivian Darkbloom and she didn't want anyone to know who she actually was. Hanna asks him if he ever figured out who she was looking for. Seth then shakes his head, and says that he didn't, but he did tell her to stop looking. Aria then asks him why and he replies that there were two people who wanted to hurt her, a man and a woman. Martha, from across the room, tells Seth to hold his tongue. Spencer asks her when this "man and woman" came into the shop. Martha replies that they never did and it was something Seth saw in his head as he was "gifted and could see things that hadn't happened yet". Spencer then went on to ask Seth about what the couple looked like. Seth answered that they had dark hair, like Spencer's. Hanna and Emily continue to ask if the woman was wearing sunglasses and had a cane, and whether or not she was blind. Seth then says that the woman could see perfectly fine. Martha interrupts the conversation by telling Seth to go upstairs and put the groceries away. He nods, but then says to the girls that he is sorry about what happnedd to her (Alison), and that he would hate to have dirt in his lungs (telling the audience that Ali was buried alive). Martha then tells him to go upstairs again.
After the barrage in the doll hospital and the Liars flee from the shop, Martha is seen telling A that while she kept her deal, the giant mess she has to clean up was much more than she bargained for. But then A hands Martha an envelope full of cash and a large lollipop to Seth, who stares back uneasily.