Dr. Flint's pursuit of Harriet/Linda forced her to live a life of bizarre captivity stowed away in a tiny space above her grandmother's shed. Having no rights of her own--either personal or legal--her unorthodox plan to thwart Dr. Flint failed and her life was all but terminated as she chose between the two things that seemed all that was left to her.
You may want to go to Google Books and then search for Harriet Jacobs in relation to each of the other persons you mention. For example, you could search for
Harriet Jacobs and Dr. Flint
Harriet Jacobs and Mrs. Flint
Harriet Jacobs and her mother.
Here's what I found when I searched for the first pairing:
The early death of her mother clearly had a massive impact on the life of Harriet Jacobs, and forced her to become aware of her state of being a black girl in a world dominated by whites. It obviously meant that she had to become very strong and independent very quickly, as she lacked anybody to look after her or to protect her.
Flint is actually the pseudonym of Dr. James Norcom. When Harriet wrote Incidents in the Life of a Slave Girl, she changed the names to protect herself. Flint/Norcom's largest influence on Harriet's life was her decision to have two children with a white neighbor, Mr. Sands/Samuel Sawyer, in the hope this will cause his lust to diminish. It does not work, though, and she is forced into hiding to keep herself safe and ensure a better life for her children.
Harriet's mother died when she was only six years old. Until her mother died, she lived a happy life and barely knew she was a slave. Flint tried to force her to have sex with him when she turned 15, but she spurned his advances. Still, it was a very difficult time for her.