There are many pairs of names that could be called Charity and Sylvia. If these are common names in a local history, perhaps they are historical figures. But in the realm of literature, there are countless fictional characters with various names. Maybe there's a new novel where Charity and Sylvia are fictional characters. We really need more information like what kind of context these names are mentioned in, are they associated with a specific time period, place or event? If they are part of a family tree in a historical archive, they are likely historical, but if they are part of a fantasy story, then they are fiction.
Gertrude Baniszewski was the main perpetrator in the Sylvia Likens story. She was the one who was in charge of Sylvia and carried out much of the abuse.
The Sylvia Likens story is a tragic and disturbing one. Sylvia was a young girl who was brutally tortured and abused. She was in the care of Gertrude Baniszewski who, along with others, subjected Sylvia to inhumane treatment, including starvation, beatings, and burning. Eventually, Sylvia died from the abuse.