I mean, she always was odd in her ditzy and dreamy ways. But once a year, she would be different. On that day, she would not not that same ditzy and dreamy girl anymore. Her hair would be straight that day. She would be a lot more serious, aggressive, and a lot less social. Lots of people, even Draco Malfoy and Pansy Parkinson would notice these changes that day. Who wouldn't? How could you expect the usually quirky bubbly girl to almost get into a fistfight with Cho Chang after she publicly insulted Roger Davies in Quidditch, even though Roger Davies was in her house. Just for 24 hours she would be that way.
Then she would be normal. Like nothing ever happened. People would eventually forget, which made sense. How were you supposed to remember that during one day out of 365 days, a girl you didn't really like acted strange.
"There's something odd about her today."
Luna heard the whispers of Hermione Granger as she sat in the corner of the library. She sighed and turned back to her battered copy of Fantastic Creatures and Where To Find Them. But she had trouble concentrating as Hermione, Ron, and Harry talked. She heard Harry defending her and Ron just plainly sitting there, wisely choosing not to take sides. Luna took a deep breath and turned around and said quite firmly, "There is nothing odd about me, Granger! And don't you think it's quite rude to talk like that behind other people's backs? Or is that what you do all the time, being stuck up?" Hermione had a shocked look on her face and looked rather taken aback. "I didn't mean to-" she mumbled, but Luna interrupted her. "No, you did mean to." Luna rushed out of the library, turned around and said, "There is absolutely nothing odd about me today, Hermione Granger!"
But nobody believed that. It was not true. Luna was not okay that day.
It was the anniversary of her mother's death.