Fiona Belmont dies three days before her seventeenth birthday.
When Professor Flitwick asked her how old she was, she lied.
"I turned seventeen three days ago sir."
She doesn't know why she stayed. She honestly couldn't say. It wasn't as though anyone asked her about it. There really wasn't time.
She could have left. She could have. Really. She could have walked out with Mara and Erica and so many other members of her house. She had no obligation to stay.
But that is not what she did. She meant to. But when she had tried to get up, her stomach dropped. And for once in her very Ravenclaw life, Fiona did something very unintelligent. She remained in her seat.
"I turned seventeen three days ago sir."
That's all it took for Fiona Belmont to become a solider. That's all it took for a sixteen year old girl who had never even considered dueling to come face to face with dark wizards with twice her experience.
Fiona Belmont dies three minutes after the battle begins, shielding a first year (why is he here, how is he here) from a killing curse.
All she could think in her last moment was that her father would have been proud of her.
He was.