Disclaimer: BtVS is owned by Joss Whedon and Mutant Enemies, Harry Potter is owned by J. K. Rowling and Warner Brothers. I do not make money off this story and will return the characters to their respective owners unharmed.
Warnings: Character deaths
She walked through the dark, deserted hallways, quietly making her way towards the room of requirements. She missed him already though it had only been a day since their last meeting. As Dawn Summers came to a halt in front of the wall that hid her destination she paused to ponder her decision again. She knew that helping Draco breach the school wasn't right, it was not something her sister would approve of.
Then again that was part of the reason for doing it, a way of finally stepping out of the Slayer's shadow. Be her own person, be something more than just the kidnappee having to be rescued, or the tag-along always desperate to be included in the action, and always, always being pushed aside. Not strong enough, not old enough, not skilled enough. For her it always came down to a simple fact, she was not enough, would never be enough for her sister or anyone else. But here with Draco, she was the special one, the useful one, in fact he would not be able to complete his plan of letting the death eaters into Hogwarts without her. Without the powers being the Key had provided her with. That was why she would do it, why she would open the portal and let chaos into the school she had been sent to three months ago, to keep her safe, of course.
She was so tired of being pushed aside, being kept safe like some precious heirloom and not a person made of flesh and blood. She would show them, with this one action she would never again be ignored, she would be more than just the Slayer's kid sister, she would matter, her name would be known by all. She liked the idea of that, being famous, for her actions instead of for her creation. Yes she could live with that.
Dawn opened the door and was meet by her boyfriend who quickly locked and warded the room. Then after a short kiss, she took the silver dagger he handed her and opened up a vein in her wrist, while his voice started chanting a spell that would focus her portal towards the death eaters standing by in his father's manor. She felt her blood drip off her fingers and watched as a green portal slowly opened in the air in front of her. Five minutes later the portal was big enough to allow the first of the masked men to come through. Seven minutes later the room of requirements housed not only herself and Draco but also twelve death eaters. One of the men took off his mask and bowed slightly to her in respect, his similarity to her boyfriend was uncanny and she easily recognized him as Draco's father, though she had never met him in person before.
Then as she watched on in satisfaction they all took their leave of the room and went out into the school, five of them going to the Gryffindor tower, to which she had given them the password, while the remaining seven went to the headmaster's rooms. Dawn smiled again, after this Buffy would see her, would know her, would recognize her as something more than just energy made flesh. After this she would finally be real.
Five hours later Dawn was back in the room of requirements, this time she was neither excited, nor happy, this time she was filled with the dread and remorse that only came when you had done something so stupid, so awful, so earth shattering that it could not be repaired. She slowly sank to the floor, tears streaming down her cheeks as she thought of the hours that had gone before. She didn't know how it could have happened. When Draco had told her of his plan she had known it was to kill Harry and Dumbledore, she had known that it would be a battle, that people, students, children, would die.
But she hadn't known, not really, it had all been an adventure, a silly game between her and her boyfriend, like playing chicken, seeing how far you could go before you got scared and put a stop to it. Problem was that no one had stopped it, no one had told her that it was real, that innocent people would be killed. Killed by her, by her actions, just because she wanted to feel real. She closed her eyes, the faces of Dumbledore, Harry and the 17 students who had died that night flashing before her eyes. Slowly she took the silver dagger Draco had given her the night before, it seemed like a lifetime ago now, she raised it up, looking at the light reflecting off its razor sharp edges and plunged it into her heart.
The last thought on her mind was whether or not she would leave a body, would she be real enough for that?