A/N- The title, which is rather unimaginative, will probably change soon.

She'd been living on the streets for years by the time the letter came. She didn't know that it was for her, when she woke up and the envelope was lying beside her. She didn't know how to read the words scrawled on the front in emerald green ink, or she would have known that it said:

Miss Cassandra Cain

Behind 4 Thackerey Road

London

She picked it up, turned it over, looked at it to check it wasn't dangerous. Then she shrugged, dropped it back on the ground, and walked away.

The next day, she was awoken in the early morning by another envelope landing just beside her. She knew that it was one of the ways other people communicated, the ones who used words she didn't understand instead of reading body language and gestures. She ignored it, thinking it must have been intended for one of the homes nearby, and went to scavenge some breakfast. She went to a different alley this time and slept beneath a dumpster. The smell might've been terrible, but it was warmer than sleeping in the open and the grey skies indicated that it would rain.

She wrapped herself in a stolen coat and hoped it wouldn't flood.

The noise that woke her came out of nowhere. One moment, she was sleeping lightly, the floor damp beneath her, subconsciously aware of the sound of the rainfall and the drunken party that had passed ½ an hour before. The next moment, a great crack sounded like a gunshot. Cassandra was awake immediately and rolling behind the dumpster, putting it between her and the gun until she could assess the situation. She was small, so there was just enough space between the dumpster and the wall. She peeked over the top. To her surprise, she could see no sign of a gun. There was a woman standing in the alley, facing the other way. Cassandra hadn't heard her approach. She wore an emerald green cloak and her hair was pulled back into a tight, severe looking bun. She was clearly turning around as if looking for something, or someone.

She was also holding a weapon that emitted some kind of light. It looked harmless, disguised to look like a wooden stick, but Cassandra could tell by the way the woman held it that it was a weapon. Despite this, the woman didn't seem as if she was preparing herself for attack. She called out gently.
"Cassandra? Cassandra Cain? I mean you no harm. My name is Professor McGonagall. Are you there?"

Cassandra didn't understand the words, but she recognised one. Cain. That word had been used a lot when she'd been with Him. Her father, the one who taught her to fight. The one who taught her to kill.

She could tell by the woman's body language that she was worried about something- no, someone. A person who she thought was in danger. She wanted to help them.

Cassandra didn't dare show herself. This woman had to be an associate of Cain's, and that meant she was looking for Cassandra. It meant that she would try and take Cass back to the man she'd run away from.

McGonagall flicked her wand. "Homenum Revelio." She pronounced, and then suddenly Cassandra felt a swooshing kind of sensation, like the wind was rushing past her, and McGonagall turned towards her hiding place. Cassandra ducked down behind the dumpster again, breathing as quietly as possible. She prepared herself for fighting.

McGonagall's face twisted with a mixture of horror and pity as she approached the dumpster. With another flick of her wand, the dumpster suddenly leapt away, leaving a terrified Cassandra exposed.

She didn't stop to think. She did what she was trained to do and attacked. She didn't want to hurt this woman, but if she was an associate of Cain's, Cassandra couldn't risk being found. She leapt at the woman, hit her to make sure she'd fall unconscious, and ran.

She was too busy running to register more than a flicker of surprise that the woman hadn't reacted as if she even realised she was under attack, and certainly showed no indications of being a trained fighter or assassin like Cain.

She didn't sleep that night. First she went to a big department store and stole new clothes, leaving the old ones hidden in a bin a few streets away from the shop. Then she started walking.
She didn't know where she was going, but she knew what to look out for. Once she reached a train station, she watched as people exchanged bits of white and blue paper for the orange tickets that you needed to get onto a train platform. She knew by now that simply leaping over the barrier would attract the wrong kind of attention. Although none of the police were remotely capable of catching her, she didn't want to make it easy for that woman or anyone else to find her.
She mixed with the crowd for a few moments, watching those boards filled with unintelligible figures. Then her hand slipped into the pocket of the young man standing near her, and she took his ticket and was gone without him ever realising that he'd been robbed. She walked straight onto the platform and into the first train that came.

At the first stop, she got off the train and walked to another platform before getting a train that was moving in the opposite direction. Then she found a seat and sat down to wait.

Several hours later, when the train stopped at a station for longer than the usual few minutes and everyone in her carriage stood to disembark, Cassandra followed them, losing herself in the crowd. She was in a completely different area this time, and it had been about 14 hours since she'd run from the woman in the alley. Still, she wasn't going to stop yet. She'd had time to rest physically on the train, and there was no need for her to sleep now. She stole a backpack, some food and a blanket from houses nearby and started walking.

The aim was to get as far away as she could from that alley, so that even if her father found out she'd been to the station, he wouldn't be able to find her. She couldn't go back to him. He'd fight her and shoot her and ask her to kill, and she would never, ever kill again.

She walked all that night and most of the next day before they appeared. Shortly after dusk, when Cassandra was considering finding somewhere to sleep (seeing as there had been no sign that she was being pursued, and even she could only stay awake for so long), she heard that same cracking sound, the one that sounded just like a gun shot. Then more. Alarmed, she whirled around, half-expecting to say David Cain standing there, pointing a gun at her and expecting her to dodge the bullets. Instead, she was shocked to see that she was surrounded by numerous figures in cloaks, all holding the same wooden stick weapons that the woman from the alley had used.

She was already moving when the beams of red light shot from the wands. She dodged 3, 4, 5 beams before one caught her in the chest and she fell back, stunned. She felt a burst of terror before she fell unconscious.

When she woke up, she was restrained. Thick ropes tied all of her limbs to a bed on which she lay, and the woman in the emerald green cloak was standing beside it.

An elderly man with a long white beard and equally long white hair stood next to her. Both were looking at Cassandra.
They already knew she was awake, had probably used medicine to wake her up themselves, so she didn't try to hide the fact that she had regained consciousness. Instead she screamed and writhed, trying to find some weakness in the rope, but it just seemed to get tighter everytime she pulled at it.
"It's alright, Cassandra!" The old man said. "We're not going to hurt you."

His body said intelligence, subtlety. This was a man capable of ruthless manipulation. His bearing said he wanted to help her, but he would be a very dangerous foe.

She didn't stop moving. She could lie with her body, maybe she'd finally found someone else who could. Besides, other people had thought they were helping her in the past and only made things worse.

"Poppy, can she understand us?" McGonagall called questioningly. Another woman bustled over and lay her wand against Cassandra's forehead, though Cass bared her teeth and pressed as far as she could against the mattress. Thankfully, the woman didn't seem to want to cause her pain, and although strange symbols appeared above her, there was no pain.

"Stay still!" The woman reproached. "Hmmm. She doesn't seem to have a grasp of words at all. Her hearing is fine, very good actually, but she doesn't understand what we're saying."

"Is she foreign? Perhaps we could find another language-"

Poppy shook her head. "It's not just English. She doesn't understand any language. Words are a total mystery to her. In fact-" She held the wand above Cassandra's throat, something which made Cassandra protest more despite knowing the woman meant her no harm. She was restrained and someone was holding a weapon close to her throat. How could she not be afraid?

Poppy closed her eyes briefly. "The poor girl. She's never been taught to speak. I doubt she's ever articulated anything at all. Her vocal chords are weak, as if they've never been used."
Her body said she felt pity, sorrow, sympathy, horror. Cassandra bristled. She didn't need their pity!

"She must have been raised in total isolation." Poppy murmured. "Not allowed to learn to speak or even hear a voice until she'd passed that stage of her development."

All of them looked horrified now, and even concerned. They looked at Cassandra as if they both pitied and feared her.

Cassandra collapsed against the bed, finally stopping her struggles and pretending to be exhausted. She'd noticed that every time the ropes started to weaken, the elderly man's wand would twitch and they would be tighter again. She didn't know how he was doing it, but she was sure he wouldn't let her escape while he sat there. She concluded that she would have to wait until they left and then try dislocating her thumb to slip her hand through the bindings. Once she'd done that, she should be able to free her other hand and untie the bonds. She stretched her hands, making just a little more space for herself, and held them still in a stretched position. If the rope tightened again it would be painful, but she could tell that they didn't mean her harm. That didn't mean she was safe, seeing as she didn't know who they were working for, and she wasn't going to remain a prisoner even if they were harmless.

Unfortunately, her apparent collapse didn't seem to encourage them to leave her alone.

"I don't know any spells that could help." Madam Pomfrey murmured.
"Nor I." said Dumbledore, his voice sad. "I doubt if a child like her has ever existed before."

"Must we tie her to the bed?" Pomfrey asked, frowning. "It must be terrifying for her."

McGonagall sniffed. "She attacked me and knocked me unconscious without provocation, Poppy. I don't think we can risk removing the bonds until we find some way to communicate."

"Perhaps Professor Snape?" Madam Pomfrey suggested. "He's a legilimens. If he can just figure out how she communicates, we could at least explain that we mean her no harm."

McGonagall frowned. "But how can we teach her? She's violent, and if she can't understand us I don't know what we can do. She would never be able to follow instruction or read magical theory or even utter an incantation! Yet, if we don't find some way to help her control her magic, she'll only grow more dangerous."

Albus nodded. "It would be disastrous. We must keep her here. Minerva, would you fetch Professor Snape?"
Mcgonagall gave a curt nod and left, still frowning.

Madam Pomfrey looked down at the girl. Cassandra's face was carefully blank, but she thought she could see confusion and fear in the girls eyes.
"I'll contact St Mungo's. Not officially- they'd put her in a high security ward with prisoners, and I'd hate to see what the Ministry would make of this. Still, I can ask some specialist Healers there about mind magic and ways we can help her. Maybe even present it as a hypothetical case. If you'll excuse me, Albus."
She turned to walk back to her office, hoping she could find something useful.

Albus stood and watched the girl for several minutes with his piercing blue eyes. She stared definitely back at him. He gave her a small smile and turned to go, whistling.

Finally they'd left her alone. Cassandra concentrated, gritting her teeth as she dislocated her thumb in order to pull her hand from her restraints.
Moments later, she was gone, running as fast as she could down a long corridor. There were portraits on the walls, and ancient looking suits of armour. She saw one with a sword that looked like it was in passable condition and leapt at it, trying to grab the sword to defend herself.
She gasped in horror as the armour, which she had been sure was empty, moved and a steel hand grabbed her hand and twisted until pain forced her to drop the sword.

She didn't understand- it wasn't alive, it couldn't be but that hadn't prevented it from acting like it was. Was it a machine, a new kind of security system? Perhaps.
Rather than trying to take it again, she ran. Before her, a pearly white person emerged from a solid wall. Afraid of what seemed impossible, she kicked at the creature and nearly fell when, instead of colliding, her foot passed straight through.
"Petrificus Totalus!"

Cassandra felt something hit her in the back. She suddenly fell forward, unable to move. She was terrified. Why couldn't she move? This had never happened before!

She couldn't stop herself from landing face-down on the cold floor. Two sets of footsteps approached. She could tell from the sound that it was McGonagall and one other.

"This is our new student, I presume?" The voice was male, cool and smooth, and the tone was sinister. A hand reached out and grabbed her shoulder, pulling her over so that she was facing upwards. Try as she might, Cassandra was helpless to stop it.

When the hand released her, she was looking up at a sallow-faced, hook nosed man with black eyes and hair. She tried desperately not to look afraid, to lie with her body so that he didn't think he'd won, but her muscles wouldn't move. Nothing would.

"Did you have to hit her in the back, Severus?" McGonagall's voice sounded mildly disapproving. "She'll have bruises."

"Quiet." Snape snapped, looking into Cassandra's eyes. She felt a strange sensation in her head and imagined kicking it away. It didn't work. She imagined attacking this feeling- it seemed invasive, wrong, like it shouldn't be there- with all of her skill. She saw Snape flinch and the feeling receded for a moment. Then suddenly it returned, stronger than before. She was suddenly swept up in an old memory-

Cain shooting at her while her back was turned, sparring with him, that final moment when she'd run away. She saw a brief flash of the man she'd killed looking down at her and rebelled against the memory with everything she had.

The feeling vanished. Snape drew back. He seemed shocked.

"She reads body language." He murmured.

"Excuse me?"

"She can't understand words, but it seems like Miss Cain can read body language to an incredible extent. She doesn't think in words, but gestures and movement. Simply by looking at your movements, she can tell what you're feeling, what you'll do next, and even some of what you're thinking. But her understanding is different from ours. She knows we communicate with words, but she can't understand them at all."

"Remarkable." McGonagall said, astonished. "But why did she attack me?"

"She lives on the streets." Snape replied. "Even someone trying to help her could inadvertently return her to her...father, I think. He did terrible things to her to make her this way."

Snape looked carefully at Cassandra. Trying to make his intentions clear and seem open and honest (something he didn't usually strive for), he said slowly , "We want you to stay with us. We will give you food and protection. We mean you no harm." He flicked his wand and suddenly Cassandra was free, able to move again.

This time, she didn't run. She was certain that Snape had seen her memories as she had, and she'd watched his reactions to them. He'd been horrified by David Cain, and so was McGonagall. They wouldn't return her to him, and whatever weapons they had were more dangerous than anything she'd previously encountered. She might not be able to leave.

She stood up slowly making sure her face and body gave away nothing. They'd learnt enough about her already.

McGonagall held out a hand towards her, moving slowly as if trying to avoid startling a frightened animal. Her voice was kind. "Will you come back to the Hospital Wing? We won't force you, Cassandra."

Cassandra didn't know the words, but she knew what they wanted. She didn't take McGonagall's hand. Instead she started walking towards the room she'd escaped from. She'd be careful, though. She wasn't about to let them tie her up again.