Jonah

Not much is known about this character, other than he is an "informant" of Vivian Darkbloom/Alison DiLaurentis's. He makes his first appearance in Season 2, when his phone number is discovered in the pocket of the trench coat belonging to Alison's persona Vivian Darkbloom. He worked for Allegheny Cellular until Vivian got him fired.

First Appearance
Jonah is first introduced in "The Naked Truth" as a random number found in Vivian Darkbloom's trench coat pocket.

At first when the girls call the number, they leave a voicemail, but later on when they call back, a woman answers the phone, annoyed because she doesn't know anyone named Vivian, and tells them to never call again. Later on that night, a man repeatedly calls them back from that number. When the girls call back, the man reveals that he knows Vivian, and he agrees to meet them somewhere in order to talk.

More on Jonah
In CTRL: A the girls choose Aria as their figuere head, and all go out to a diner to meet with the man. He sits down and asks Aria how much Vivian owed her, to which Aria is shocked to hear. The man says that Vivian cost him his job. Aria asks what Vivian did, and he explains that he worked at Allegheny Cellular in human resources, and Vivian wanted information.

Aria asks what information Vivian wanted, and the man smiles and says that she must be Alison. Surprised, Aria asks if Vivian told him about Alison, and he reveals that Vivian told him about a friend named Alison who was getting texts from somebody, but the number was blocked and she wanted to know where they were coming from, and would pay to find out.

Aria asks if he found out, and he says he did, but made the mistake of telling Vivian before he had the money in his hand, then got fired for accessing restricted information, and cheated out of $2,000. Aria asks what he knows about the person sending the texts, but the man says he's not talking without the money Vivian owes him. He tells Aria to never call that number they found again, and instead writes down a new number. As he gets up to leave, Aria asks who she is supposed to ask for when she calls, to which he simply replies, Jonah.

In the episode Breaking the Code, Aria and Spencer meet Jonah at the park. They give him the money, and he gives them an address. Unsatisfied with just an address, they ask him for more. He says that's all it is and that when he gave Vivian the address, she was happy with it. With that, Jonah leaves.

In Father Knows Best Aria receives a call from Jonah, telling her to go to an address, revealing that in addition to the law firm, Alison was also getting texts from that general block area, and that it may reveal information to her and her friends about Vivian's true intentions. The Liars get there and discover a nearby doll repair store filled with dolls that similar to those that once haunted them before.