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 later caused the reveal of New Amsterdam to Muggle New York, dubbed the Night of the Unveiling, thus shattering the Vow of Secrecy, as well as ultimately setting forth a chain of events that led the destruction of the universe itself. However, the latter events were undone when she traveled back in time with James Potter and sacrificed her life to save him and his family. Decades later, she became the new Gryffindor House ghost, dubbing herself the Crimson Thread.
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. Regardless, Petra and Izzy became very close, forming a unique bond over the years.
She attended Hogwarts School of Witchcraft and Wizardry, and was sorted into Gryffindor House.
In her first year, she became close friends with Donofrio Odin-Vann, who was a seventh year at the time. Both of them having in common a similar family situation. As Odin-Vann would later describe, “I had hardened a bit. Petra had not yet hardened. And in my heart, I didn’t want her to. So I befriended her. We became secret allies. I watched out for her. It was a brief but important acquaintance.”
By the time James Potter had started at Hogwarts, Petra was already in her sixth year, in which she also had a brief relationship with Teddy.
She later became close friends with James, who privately formed a crush on her despite their age difference.
Petra eventually discovers much darker secrets about herself, being that her mother Lianna (still pregnant with Petra at the time) had made a deal with Lucius Malfoy. Unbeknownst to her, he was trying to carry out a final request from Voldemort. That in the event his plans would fail and himself defeated, he secretly made an "eighth" hocrux (in the form of a dagger) to entrust to Lucius. The goal being for him to use it to draw blood on the mother of an unborn baby, thus allowing the offspring to inherit the final shred of Voldemort's soul, and create a "Bloodline," or a supposed successor.
Because Petra's mother was unaware of this plan, Lucius is able to use the dagger to carve into Lianna's womb, allowing Petra to inherit the shred of soul. Though her mother died when finally giving birth.
Following this revelation, she later discovers that she is more than just an ordinary witch, being the first sorceress in history.
- Petra is a feminine given name, and a form of "Peter." Derived from the Greek word, petros, meaning "stone" or "rock." In this case, Petra's name is short for Petracia (commonly spelled, Patricia), which is derived from patrician, meaning "noble." Also being a female form of the name, Patrick.
- Zoe is also a name of Greek origin, meaning "life, alive." Which is also a calque (or "copied translation") of the Biblical name Eve from the Book of Genesis. In the Vault of Destinies, references are made to the fact that New York is nicknamed, "The Big Apple." And in the Biblical story of the Garden of Eden, it is said that Eve had to do with the fall of man by taking an apple from the Tree of Knowledge, giving turmoil to the rest of the world because of it. Just like how Petra revealed New Amsterdam to Muggle New York (the Big Apple), and gave forbidden knowledge of the Wizarding world to the rest of the world at large.
- Morganstern is a German surname meaning, "morning star."
- Morgan (Petra's alternate name) has Welsh (Celtic) origin, deriving from the meaning of "sea" or "sea-born." Directly relating to Petra's sister fate connection with the water able, Lady of the Lake. In legends and folklore of Merlin, Morgan le Fay was often portrayed as studying the ways of magic under Merlin, similar to how he was Petra's headmaster in James Potter. Many stories and texts also portray her as an enemy of King Arthur, and often inferior to Merlin himself, both having unique magical abilities. Just like the confrontation between Petra and Merlin, both being more powerful than the average witch or wizard.
- 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(James and Harry Potter's ancestor), 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.