Marcella Blaise Riddle had a convoluted personal history that was as much myth and legend as fact. At the time of her death, Riddle was said to be of both Gryffindor and Slytherin bloodlines, stories she was quick to perpetuate herself.
Marcella Riddle was sorted into Slytherin during her time at Hogwarts. Her parents died when she was young, and Marcella was raised in an orphanage from a young age. Although her Muggleborn bias had developed due to her upbringing and she found herself in constant contention with them while at Hogwarts, in time, Marcella came to realize that coexistence was inevitable. During her time at Hogwarts, Marcella was the Slytherin prefect for almost one full year (her fifth).
She died mysteriously in 2050 during the End of Term ball to celebrate the conclusion of the H.I.T. No one is quite sure how or why she was murdered, although there was much speculation at the time. One moment, she was dancing with several friends on the dance floor and enjoying herself. The next, she had been magically struck down, dead before she hit the ground. Four people were murdered at that End of Term ball, although little is known about the event to this day.
If her murder was an attempt to remove Marcella from the school, it was a failed attempt. She continued to haunt the halls of Hogwarts, especially the Slytherin dungeons that were once her home. Once Marcella was considered old enough to have 'graduated' from Hogwarts, she was asked to teach Divination.
At the end of 2051, Marcella found a potion in the Book of Mysteria that purported to bring spirits back to their physical form.