“Amy was Sophie's opposite in every way, from her curly brown hair and green eyes to her lower than average grades and incredible popularity.”
—Narration, in Keeper of the Lost Cities
Amy Rose Foster (A.R.F.) is now known as Natalie Freeman in the human world, but allows Sophie to call her Amy. She is also Sophie Foster's human sister and makes appearances in Book 1, Book 5, and Book 6.
She is given the name Natalie Freeman after elvin Washers erased her memories, but her original name is Amy. When she find out she has two names, she decides to use the name Amy because her parents were the one that gave it to her, not a random elf that changed her memories. In the human world, though, she must continue to use Natalie. Sophie frequently checks on her, as well as the rest of her family, with an illegal Spyball, given to her by the Black Swan in the first book. At the end of Lodestar it is found that the Neverseen attacked and kidnapped Sophie's human family; Sophie and Fitz searched the house and found a terrified Natalie (Amy) hiding. Amy remembers her when she sees her and calls out "Sophie?" It is shown that Amy knows how to make her mind silent because she overhears the Neverseen talk about listening for thoughts and is able to stay undetected. Many fans believed that this was proof that she was an elf, and several guessed that she might be Lodestar Initiative. In Nightfall, however, Amy gets her memories of Sophie back and is revealed to be only human, but is very helpful even when told to stay out of the whole Sophie's-human-parents-are-kidnapped-and-being-held-at-Nightfall business. In Nightfall, we learn that the name Amy was chosen by her parents because it meant "beloved."
- Emma Iris Foster (Mother)
Emma Iris Foster is Amy's mother. Her name was changed to Kate Freeman when the washers came to erase memories of Sophie Foster.
- William David Foster (Father)
William David Foster is Amy's father. His name was changed to Connor Freeman for the same reason as above.
- Sophie Elizabeth Foster (sister)