She becomes the Guardian of Warehouse 13, when, with Adwin Kosan's aid, Phillip Petrov transfers guardianship to her during Stukowski's attempted assassination of all three regents. Jane and Adwin Kosan survive, along with Artie and Myka who are in the building as well. Jane is revealed to Pete as a Regent by Myka, who was unaware of their connection.
She used to be an elementary school teacher, which is part of the reason she was chosen to be a Regent, because of her insight into children. She quit being a Regent for a while after Pete and Jeannie were born, but her husband convinced her to go back. However, she didn't take his advice until after he died. Her husband was (as per Warehouse rules) the only person that knew about the Warehouse and that she was a Regent.
In the following episode, "Shadows", she attempts to explain to Pete why she couldn't tell him. Jane also mentions that the name of the organization, A-Z Technologies, sounds familiar. To pinpoint where she had heard this name, she and Pete go into her memories. Jane remembers that "Aztecs," presumably the name of his team, was written on a boy's baseball cap, and that she had to take an artifact away from him due to the artifact's malicious tendencies. The artifact was Collodi's Bracelet, and was in fact the only means by which the boy could walk. That boy was Walter Sykes and he would grow up to become the man attempting to bring down the Regents and the Warehouse. The bracelet gave Sykes the ability to walk, and when Artie, MacPherson, Irene and Jane herself bagged it, the boy instantly became unable to walk. In the final episode of Season 3, Jane pointed out to Sykes that the bracelet cost him his humanity, but he didn't want to hear it.
Jane returns in "An Evil Within", confronting Artie and Claudia and informing them that the Regents have decided to allow Claudia to use Johann Maelzel's Metronome to bring Steve back to life. She guides Claudia through the process of using the Metronome, and doesn't reappear until Claudia is confronted by the Regent Adwin Kosan, who reveals that Jane had lied about allowing the Metronome to be used.
Despite being a Regent, Jane Lattimer is very kind-hearted, which probably stems from her old job as an elementary school teacher. It appears that she feels a lot of guilt for keeping secrets from her family and following her strict duties as a Regent, which perhaps leads her to allow artifact-usage among the agents despite the warnings her fellow Regents give.
Notwithstanding her personal feelings, she will try, most of the time, to fulfill her duties as a Regent and keep the agents from doing anything reckless, as well as withholding any information they shouldn't know.
Like Pete, Jane has watched many movies throughout her life.