|“||Piper, we are not going to turn this into a media circus. I’m sure he’s fine. He does take off occasionally. He always comes back.||”|
–Jane, in The Lost Hero
She starts out as Tristan McLean's assistant. In one of Piper McLean's flashbacks, she reports Piper to her father for stealing a car. She is later manipulated by Medea into telling Tristan that Piper was in danger, causing him to fly out to Mount Diablo where he was captured by Enceladus. Piper eventually called her from Camp Half-Blood to ask her where he was, as she hadn't been able to get a hold of her father for a few days, and quickly caught on that Jane didn't know and hadn't even called the police. When Piper told her she had to call the police, Jane quickly said that Tristan disappears sometimes and he would be fine, before hanging up on Piper.
Later, while in Medea's department store, Medea contacts Jane. Piper learns that Medea was charmspeaking her in order to get to Piper's dad. She was the one that told Jane to tell Tristan that Piper was in danger, resulting in his capture. Jane was so much under Medea's influence that even when Medea insulted her, she happily agreed. After Piper manages to save her father and get him to a hospital, Jane was fired for not reporting that he was missing, and was replaced by the wind spirit Mellie.
It was revealed that Jane was working for Caligula of the Triumvirate Holdings. She, along with Tristan‘s accountant and film agent, were in on the emperor's plan to destroy everything Tristan built and cause him to go bankrupt.
Jane isn't exactly bad, as she was controlled by Medea, a sorceress, in The Lost Hero. Piper disliked her before she was controlled, implying that she was always a mean person. This is most likely due to the fact that Piper felt that her time with her dad was always interrupted by Jane coming to talk about business. She had an "organized mind" according to Medea.
In The Lost Hero, it says she has hair "swirled tight into a bun."
- In The House of Hades, she is mistakenly referred to as "Jessica" because Rick Riordan simply forgot her name. 
- Riordan joked on Twitter that her full name was Jessica Jane, but her friends called her JJ.