Warnings: Language, violence.

Spoilers: None. AU.

Disclaimer: Not mine, etc.

Notes: Infinite thanks to Chichuri for encouragement and beta reading. Her story, "Slip off the Choke Chain" is remixed at the start of the last chapter of "Dark Matter." Written for scifibigbang

Prologue: I've got this feeling that there's something that I missed.

In the darkened observation area behind the one-way mirror three people in gray business suits watched a room full of children playing. If one didn't know otherwise, it would appear to be a pre-school, maybe a class of kindergartners. The watchers occasionally commented on a particular child, took notes relating to the way certain children interacted with others. All of the interactions were interesting to some degree but their attention eventually focused on a trio that had isolated themselves from the others.

The girl was reclusive by nature, even more so since the last incident. Blond hair brushed her shoulders and her pale hazel eyes were somber. She seemed to have grasped the repercussions of what she had done, however accidental the fire might have been. She had become more withdrawn than usual, worrying parents who were threatening to remove her from the program, which was not an option any of the three adults present were willing to entertain. Her back was pressed into one corner of the room, knees hugged to her chest. Her shoes, as usual, were nowhere to be seen.

Her companion's white-blond hair was bowl-cut around his head and his eyes were bright blue. He was younger than the other children, smaller, but gregarious and cheerful. He was building towers of blocks and had surrounded them with a forest of the colorful structures. At the completion of each tower he patted the girl's arm, pulled at her hand and pointed to his newest building. The watchers could see his tiny shoulders lift and fall as he sighed and started building again.

The newcomer to the group was driving a little car around the towers, careful not to knock them over. His dark, curly hair set him at odds with the blond pair. So far, he had not made any effort to interact with the girl, which was disappointing to the adults. They were running out of time to get this particular pair back on track or face losing them completely, and while they questioned the children's stability, their ability was never in any doubt.

The blond boy, Nick, stopped building when the other boy pushed the car near him. He smiled and Peter smiled back at him. Peter pushed the car towards Nick and Nick rocked it back and forth with one finger. More cars appeared from the dark-haired boy's pockets and the two of them played. Words like "promising" and "stabilizing" were passed among the observers. The girl watched, expressionless.

Nick patted his partner's arm again and held his little car up to her. Her head cocked slightly to the side as she focused on the toy. Peter tried to hand her a car, encroached a little too deeply into her space and she sank her teeth into his hand. He howled and backed into one of Nick's towers, scattering the blocks. The look of despair on the smaller boy's face was clear even from across the room. The girl hissed in anger and Nick started to cry. The change in her was immediate. The impassive mask dropped and she comforted him, knelt beside him and wrapped her arms around her partner. Peter sat near her, rubbing his hand but making no attempt to leave. He inched closer until he was pressed up against her side. When Nick stopped whimpering he returned his attention to his towers. The other two joined him, offering him blocks, helping him reach the tops of the tallest towers.

Those watching declared the experiment a success. After all, eventually Olive bit everyone.