Who is Melissa from The Forgotten Daughter and what is their importance?

Melissa, originally from the Greek island of Eresos, is a slave and surrogate mother figure to Chloe, the daughter of her best friend, Chloe. Melissa is loving and caring, and oversees Chloe's development into young womanhood. She attempts, with Chloe, to escape to Greece, but is captured in the process, and becomes ill. At the insistence of Laevinus, Melissa is brought back to health, and is then liberated.