Tom was pleased to discover that Hermione was, indeed, every bit as good at dueling as Pansy had said and that, even with his intimate knowledge of the dark arts, he failed to recognize multiple different spells she threw at him. She was almost as good as him, if he was being honest, and their duel lasted at least ten minutes before he won. He recognized that she would be as good as him if she took it more seriously but, as it stood, he was unconvinced that she could even cast a proper crucio on him. There was no part of her that was ever trying to harm her opponent, even though they were dueling with dark magic. Luckily for him, he was sure that was something he could remedy over time.

It had been a week since he first dueled her. In that time, she hadn't said anything else about immortality or the Mirror of Erised, thankfully. He was certain that there was more going on with that than she wanted him to know but he couldn't confront her about it because, in doing so, he would reveal himself to her, which he couldn't risk doing in case she truly did not know anything. Rather, he watched and waited and continued to duel her. At the moment, he had just won their seventh duel and was standing over her with his wand at her throat as she grinned up at him. They were alone in the Room of Requirement and yet she was perfectly at ease with him.

'That was positively splendid, Tom.' As usual, he offered her his hand, which she took, and helped her to her feet. 'Thank you.'

It was then that he noticed that, during their fight, his locket had slipped out from his shirt and was hanging loosely against his chest. He went to put it away but Hermione stopped him, catching his wrist with her hand.

'When you first arrived, Pansy told me you had a locket and that Draco and Theo seemed to think it's important. What is it?'

'A magical object. A dark one.'

'May I see?'

Surprisingly, he nodded, freeing his wrist to hand the it to her. Since the locket was still around his neck, this had the . . . unfortunate result of bringing them closer together. She was close enough to him, examining the locket, that he could feel her hair tickling his nose.

'How did you get Slytherin's locket?' His eyebrows rose.

'You recognize it?' She nodded. 'It's a family heirloom. I am a direct descendant of Slytherin.'

'How did it become a magical object? It was only ever a normal locket.' He smiled.

'I made it one.' Her face lit up with excitement.

'Really? What did you do to it?' He paused, debating if he should say anything, before deciding that he could always obliviate her if he needed to since, after all, he was rather good at charms.

'I made it into a horcrux.'

'What's that?'

'It's when you split your soul and store part of it in an object.' He leaned in a tiny bit, diminishing the already minute distance between them, and lowered his voice. 'That locket houses half of my soul.' He was a bit surprised that she didn't look scared or even concerned but, rather, was smiling.

'So I was right and you are immortal. How do you make one?'

'By killing someone.' She didn't even flinch.

'Who did you kill?' Her voice was a whisper now.

'My mother.'

'Why?' He sighed and drew back from her, putting more space between them.

'She was a disgusting, horrible woman. I was conceived because she drugged the object of her infatuation with a love potion and made sure to get pregnant and, once she knew she was, she stopped giving him the potion, thinking that my existence would ensure that he would stay with her. She was wrong and he left. When I was born, she wanted nothing to do with me, since I had failed to accomplish the one thing I was made to do and she left me at a muggle orphanage.' Hermione was quiet and her expression was dark.

'I'm glad you killed her; she deserved to die.'

He was well and truly shocked. Hermione Granger, prefect, Gryffindor's princess, who he had decided was failing to meet her potential because she couldn't mean it when throwing dark curses, just told him that she condoned him murdering his mother.

'I can honestly say that I never thought you of all people would approve of murder.' She shook her head.

'There is a big difference between justice and cruelly ending the life of an innocent person. What you did was essentially give her the death penalty for rape and child cruelty.'

'I'm . . . glad you feel that way.'

'You know, I've never killed anyone, but I did keep an unregistered animagus in a jar for a year- she's a beetle. Fourth year, we had the Triwizard Tournament and this horrid woman wrote awful things about the champions and the people around them even after Dumbledore banned her from coming here and it all got published in the Prophet. Once I found out about her being a beetle, I trapped her in a magically reinforced jar before I let her out on the condition she never write for a paper again. My point here is that that could have been considered cruelty but it wasn't, it was justice because she deserved it. After all, the champions and my classmates weren't her only victims, she had ruined lives before then.'

As she spoke he realized that she was telling him all of this to make him feel better, to share a time when she had exhibited cruelty in a similar situation. Her intention was to share something incriminating with him to even the score and eliminate the power imbalance that had been caused by him sharing about himself and would have remained had she not shared something in return. He was unsure if she did this consciously or if it had, by that point, become second nature from all her time spent with Slytherins.

'I will keep in mind that, if ever you have a problem with someone, I should keep out of it because you can simply trap them in a jar.' She laughed and, for the first time, he noticed how pleasant the sound was.

'Or, if it's bad enough, I can kill them and make myself immortal.' The corner of his lips quirked up into a small smile.

'It would be my pleasure to teach you how.'

'Do you think I could get extra credit for it?'

Before he could stop himself, he laughed. He actually laughed. He couldn't remember the last time he had laughed, it had been years, and yet, this girl, this Gryffindor with her wild hair and dark magic and dark humor had managed to make him laugh. She, meanwhile, smiled, looking positively enraptured by her accomplishment.