Petracia Zoe Morganstern (also known as Petra, or Morgan) is the only daughter of Wilfred and Lianna Agnellis. She was born sometime between September 1998 and August 1999, and attended Hogwarts from 2010-2017. After a traumatic year that led to the death of her grandfather and his wife, and the reveal of New Amsterdam to Muggle New York, she became the most recent International Undesirable No. 1.
Petra grew up without knowing either of her parents, due to her father being killed in Azkaban Prison after the Second Wizarding War, and her mother dying in childbirth. As a result, she was raised by her grandfather, Warren Morganstern and his wife, who later died from cancer. Afterwards, he remarried again to a woman named Phyllis, who had a daughter, Izabella. Because of her unkind nature, Phyllis and Petra were never on proper terms, eventually growing to hate each other with a passion.
She attended Hogwarts School of Witchcraft and Wizardry, and was sorted into Gryffindor House. She also was a member of the Gryffindor Quidditch team, and the group of mischef-makers known as the Gremlins. And for a brief time, she also had a relationship with Teddy Lupin.
In the Curse of the Gatekeeper, Petra discovers that she is the "Bloodline" of Lord Voldemort, containing the last piece of his soul. She later discovers that she is also the first sorceress in history.
- Petra is a pivotal character in the James Potter series, and the main character of The Girl on the Dock, which shows the events that take place between the second and third James Potter books. She is also the main character in the short story "Petra's Getaway," from Harry's First Christmas and Other Tales.
- Petra is the first character from the James Potter novels to appear in a non-fan fiction story. The second was Princess Gabriella Xavier, the protagonist of Ruins of Camelot.
- Petra was the first International Undesireable No. 1 in decades, due to the events that took place in the "Night of the Unveiling".
- In The Morrigan Web, Petra revealed to James that after the death of her dimensional counterpart, she had become the new Crimson Thread, and would have to leave their dimension forever in order to sustain universal balance.
- Petra was in her 6th year at Hogwarts during The Hall of Elders' Crossing, making her at least 5 years older than James. Despite this they still have a close and unique relationship, which may even become romantic in the near future.
- Strangely, despite the last name of her parents being Agnellis, Petra had her mother's maiden name, Morganstern, instead. Most likely because of being raised by her grandparents.