At one point, Harriet became engaged and was pregnant with their child. However, her fiancé died before the wedding. To save her sister the shame of it being known that she consummated her marriage before it had taken place, her sister Elizabeth raised the child, a boy they named Nate, with her own husband, Richard Gray, as if he was theirs. When the Gray family left London and moved to New York, they took Harriet with them.
When Elizabeth and Richard died a few years later, Nate and her niece Tessa were put in her care. Harriet raised Tessa well and as if she was her own, and Tessa always felt that Harriet was like a mother to her.
Meanwhile, Harriet never managed to tell Nate that she was his mother. Guilty about her lies, she let him get away with whatever he had wanted and had spoiled him. She had told Tessa that Nate was an innocent to the world, and they did what they could to protect him. Eventually, however, through some of Elizabeth's journal entries found in her jewelry box that Harriet kept as a sewing box, Nate found out that he was Harriet's son and began to resent her for keeping it from him.
Through Axel Mortmain, Nate was able to find work in London. Some time after, he sent them a box of poisoned chocolates, knowing that Harriet would be the only one to eat them. Harriet died soon after, her death appearing as if it was due to some fever.
She had blond hair and blue eyes. Tessa remarked that she greatly resembled her son if one knew to look for the similarities.
- Clockwork Angel (first mention)
- Clockwork Angel: Manga (mentioned only)
- Clockwork Prince (mentioned only)
- Clockwork Prince: Manga (mentioned only)
- Clockwork Princess (mentioned only)
- Clockwork Princess: Manga (mentioned only)
- The Whitechapel Fiend (mentioned only)