The Grey Lady has always been the ghost of Ravenclaw House. But for centuries, only a few people got to know her real identity. Her name is, or was while she was alive, Helena Ravenclaw, Rowena Ravenclaw’s daughter.
Her life wasn’t a pretty one, that’s for sure. She was born during the 10th Century, it’s highly probable that near the end of the century. She was the daughter of one of Hogwart’s founders, Rowena Ravenclaw. She attended Hogwarts School of Witchcraft and Wizardry while the founders were still running it. She, as expected, was sorted into Ravenclaw and we have to assume that her mother taught her during that time, apart from being her head of house.
This tells us that she was probably intelligent, but it seems that Helena was jealous of her mother, who was revered and respected for her cleverness and craft. So, at some point while she was still at school, she decided to steal her mother’s diadem and run away from home. We know nothing about her from this moment until she is found some time later in Albania by the Bloody Baron, who would later become Slytherin’s house ghost.
Helena recounts that the Bloody Baron had always been in love with her, but she kept rejecting him over and over. We don’t know her reasoning for this, but seeing as she was so envious of her mother and all her fame and fortune, it could be thought that she felt she was better than him.
Rowena Ravenclaw used that love he had for her daughter to ask him to go find Helena so she could see her one last time before she died. The Bloody Baron looked for her for a while until he found her in a forest in Albania. When Helena realized who was coming, she hid the diadem inside a hollow tree and prepared to confront him. The Baron told her why he was there and told Helena to come back home with him, which she refused. Then, he confessed his love for her one more time, and when she rejected him he became furious and stabbed her with a knife. Helena died from the wound, and when he saw what he had done, the Baron killed himself.
We don’t know if Helena’s ghost, now the Grey Lady, ever saw her mother even in ghost form, but we do know that she came back to Hogwarts and stayed there to watch over Ravenclaw students for centuries to come. Whether this was a personal choice impulsed by her guilty feelings or it was something forced on her, it seems she accepted her role and took it seriously.
As a ghost, the Grey Lady was seen as shy and quiet, and tended not to talk to students from the other three houses. But, for the Ravenclaws, she was always there to help them find their way if they were lost or locate any missing items. She still shows she has that need to be praised and recognised when she falls for Tom Riddle’s charms and tells him where she hid her mother’s diadem. What we can learn from this is that ghosts still maintain the personality they had while they were alive. In fact, the Grey Lady has sometimes been seen attending lessons and taking notes, which fits perfectly with a true Ravenclaw’s love of learning. Hey, at least she gets to see all the new spells, potions, and other magical inventions forever, that’s one of the dreams of a Ravenclaw, isn’t it? And, in the end, she shows her true colors when she helps Harry Potter finish Lord Voldemort, giving us a glimpse of what she has learned through the years.