Prose was a Literal who dreamed of forbidden things, namely, interacting with Fables. Going against the rules of her community, Prose began to visit different Homelands. She spent much time in the land of Alexandria where it is said that she found her "theme"--most likely referring to her job as a librarian since the great library resided in the historical Alexandria. However, this was not the thing that would have the greatest impact on her life--she met a prince, Prince Charming to be exact, and became pregnant with his child. This child she abandoned at the home of a poor Fable farmer and his wife since it was forbidden for Literals to breed with Fables. That child grew up to be Jack Horner.
The rest of her history is undefined but can be pieced together. It is known that she had two children with Bookburner: Priscilla and Robin. This information is contested by Bookburner (who told Hillary Page that he wasn't able to have any children with Prose) but proved to be factual by Bookburner's father, Kevin Thorn. Prose was then "stolen away" from Bookburner by his brother Mr. Revise, where that couple had one child, Hillary Page. This could mean that either Prose didn't want Robin and Priscilla to know their father or that she didn't want the Bookburner to know of his children. Hinting that he either change or became dangerous that she may have left her husband out of fear. Unfortunately, Prose died in childbirth and for some unknown reason Mr. Revise never told Hillary of their relationship. Hillary wouldn't stray too far from her mother's ideals as she secretly dreamed of being a Fable. She may or may not be related to Eliza Wall in some way, as Eliza has referred to the Page Sisters as her "cousins" but then again stated that Priscilla was her niece. But since Kevin has not stated having a daughter, she could possibly be Prose's sister.