Factual error: In the final scene where Solomon was reunited with his family, the doors he entered the room through had Edwardian style leadlight glass. The movie was set about 50 years before this style.
Factual error: In the close-up of the violin being strung, it is obvious the strings are of contemporary origin. You can see they are translucent plastic; not exactly historically accurate.
Answer: It was a fellow slave. As to whether or not she has a greater role in the book I can't say, but I interpreted the scene to demonstrate how far removed from his former life Solomon had fallen; rutting on the floor in front of everyone else like an animal.
Phixius ★