Everyone talked about how Severus Snape was the double agent, the Death Eater in the Order of the Phoenix, the one Dumbledore trusted even though he shouldn't.
What they didn't know was that Minerva was as well.
She and Tom (for he always would be Tom to her) had decided long ago that she wouldn't have the Dark Mark placed upon her skin, for it would be too easy then for her to be discovered as working for him, but it wasn't really necessary because while the others had his mark on their arm, she had it on her heart.
They hadn't ever really intended for her to become this, but it happened anyway.
She was always going to join Tom, that was clear. Hadn't she been the one who had found the word Horcrux in an old document and rushed to show it to him, practically grinning as he eyes lit up with excitement? "Thank you, Minerva." He had whispered then before leaning in to kiss her, his passion for power and his passion for her mingling in a single action. Even when he surrounded himself with a group of conniving Slytherins, it was the clever Gryffindor girl, two years his senior, who he spent most of his hours with, and who he gave his heart too.
He made a gift to her of the first Horcrux he made. It was a book, the very one which he had used to study Legilmency and she had used when she worked in secret to become an Animagus. He didn't tell her who he had killed to make it, and she didn't really care. She just liked turning the pages knowing that she held a piece of his soul. Though Tom valued power so highly, he had given a great deal of it to her.
The problem came when she wanted to stay at Hogwarts to teach. She had spent many years making sure that everyone believed she was trustworthy, because she always had wanted to teach there. Professor Dumbledore in particular had liked her. Tom too had wanted to teach (despite the fact that he hated children, but he never listened to her when she told him that this meant he would never actually enjoy teaching), but Professor Dumbledore had rejected him, mostly because of his lack of care in making sure that Dumbledore didn't know about his descent into darker magic.
She, however, had been given a job. They fought over that, of course. He said that she would not take the job, not if she truly loved him, and she said that was ridiculous, of course she would take the job. They didn't speak to one another for a week after that. But eventually it was decided that she could teach at Hogwarts and still be Tom's loyal supporter – if that was the right word, of which she wasn't always sure.
And that would be the way things were, she thought.
Until, one day, Dumbledore asked her to be in the Order of the Phoenix.
To refuse would arouse suspicion, and she could not do that, not if she wished to keep her job. So she joined immediately, and Dumbledore smiled, and she became Tom's spy.
After it appeared that Tom died, she devoted her energy completely to the Order. There was always the pain of being without his eager desire for knowledge and power, which she had found in no other, not to that extent, the pain of never hearing his harsh sarcasm that always made her laugh – and she was not easily amused. She became a sterner teacher than she had been before, trying to focus on the Gryffindor side of her personality, which she had so often neglected around Tom. But she knew her place was at his side. And she also knew that he was not dead. She would hold the book that held his soul and pretend she held him again.
And then, fourteen years later, he returned. She didn't know immediately, the way the Death Eaters did, for there was no way for him to tell her. But she was overjoyed, and had to contain that joy when around Dumbledore and the other teachers.
That summer, they were reunited.
She had heard stories about how his appearance had changed, but hadn't realized how dramatic that change was until she saw him. She shouldn't be upset by it, she knew that, but it was hard not to be, when his dark clever eyes were now a bloody red that was painful to look at. His voice, too, was different, rasping and harsh, the way it sounded when he spoke Parseltongue. She hated hearing him speak Parseltongue, because that was a part of him that she could never be a part of.
"You've changed, Tom."
She waited for him to grimace as she used his old name, the way he always had. But he didn't, and that, too, worried her.
"I'm not the only one who has." For a moment, his voice was almost gentle again, and she felt embarrassed at the new wrinkles that seemed to cover her face and hands, and that fact that her hair was all grey now.
But his voice was swiftly businesslike. "I can't believe that Potter boy got away. Minerva, next year you'll capture him. It should be easy enough for you, he is in your House."
An image of Harry Potter came into her mind – a gangly, awkward child with his untidy hair and glasses that always seemed to be breaking. Once he had been one of the greatest wizards alive, and now he was reduced to attempting to kill a child? A child who she had awarded House Points to, and who she had cheered for during Quidditch games. This wasn't the Tom she loved. She nodded, and tried to say something, but he cut her off. "Minerva, I'm busy. I'll discuss less important things with you later."
As much as she didn't like to admit it, that hurt, and continued to hurt as she left and went back to her home. Had she been just another of his pawns, that he used and threw away? She had never wanted to believe so. She had prided herself and mattering more to him than all those others. But now all the evidence pointed to that.
Typical Slytherin behavior. She should have known.
She took out the book that was his Horcrux, looking it over again but not really thinking about the contents, and she knew suddenly that she didn't want a piece of his soul. She didn't want to spend her life helping a man whose dearest ambition was to kill a fourteen-year-old boy.
Looking at the crackling fire in the hearth, she threw the book inside.
There. Now she was a Gryffindor again.