((Yes guys, I realize Nephilim are mentioned in spn, just ignore that and especially the fact that they thought nephilim are abominations. just go with the story as if nothing's wrong. this is somewhere in the middle of season 6. before Castiel was even thinking of taking in the souls from purgatory and after Sam got his soul back.))

Sam slowly shook himself into awareness. A beautiful voice was singing. He opened his eyes. A woman stood facing away from him, gripping the bars of their cage. Her hair looked dark brunette in the shadows. She wasn't very tall, he saw. Dean was sitting beside her, his head above her belt. He turned and saw that Sam was awake.

"Sammy," he whispered. He scooted closer and helped Sam sit up. His left eyebrow was bandaged with a white square of gauze.

"Dean," Sam grumbled, struggling to prop himself up on his arms. He stared dazedly up at the woman. "Who is she?"

"I don't know," Dean replied, staring back at her. She suddenly turned her eyes on them. She smiled at Sam.

"How are you feeling?" she asked cheerfully. She walked over the ground silently. Sam looked down and was surprised she could be so quiet. The floor was littered with what looked like mice bones, rat bones, cat bones, dog bones, and even some- "Ugh, human." She nudged away a skull with her boot and knelt next to Sam. Her hand met his forehead and her bright blue eyes met his hazel ones. He was glad it was so dark. No girl had ever just paraded up and stared this deeply into his eyes before. She nodded and sat back, Indian style in a clear patch of floor. She waited, ready to listen.

Sam and dean exchanged glances. Dean huffed impatiently. The younger of the brothers used his time wisely, taking in her appearance. Her face was slightly rounded, with the merest hint of cheekbones. Her eyes were aquamarine. Her eyebrows made her look playfully intrigued. If he couldn't have seen her face, he would have thought she was smiling. Her lips were dark pink. Her hair, which appeared to be dirty blond, was curled and slightly frizzy, falling down a little past her shoulders.

She was wearing brown leather boots and faded, slightly torn blue jeans with a leather belt. Her top was a dark gray ACDC shirt. She had a greenish gray utility jacket tied around her waist. A few wristbands encased one wrist and a black watch circled the other. Sam noticed a leather strip with a pendant tied around her neck. The pendant was an Anasazi healing charm. Little demonic symbols and devil's traps decorated the leather necklace and belt, and there was even an anti possession symbol on the toe of her left boot.

"Are you a hunter?" Sam asked finally.

"Of sorts." She smiled again. "I'm Kathryn. Bet you can't spell it." She laughed shortly and plowed on. "Call me Kat. What are your names again?"

"Sam and Dean," Dean answered, pointing between them.

"Nice to meet you."

"You too," Sam replied.

"Why were you singing?" Dean asked rather rudely. "Life isn't a musical, you know." Sam was appalled at his tone, but Kat just laughed. She didn't seem to mind it at all.

"Yea, remind me to kill myself if it ever becomes one," she laughed. "Unless it's all ACDC, Bon Jovi, and Zeppelin. That would be pretty cool. Anyways, I was singing because I was trying to get my father's attention."

"Your dad's a prisoner here too?" Sam asked, searching out between the slats.

"No, of course not," she replied with a snort. "You think I'd just be calmly singing if he was a prisoner here?"

"Wait, you mean he's close enough to hear you and he hasn't come to help yet?"

"Some dad," Dean muttered.

"No, you don't understand," she interjected. "My father is an Angel of the Lord."

Dean seemed taken aback at her words. She bit back a grin as confusion and realization flitted their ways over his handsome face. Sam didn't seem comforted, merely confused. She glanced between the brothers. They didn't look like brothers: they felt it. There was something in the way their glances were perfectly in sync that made them feel… correct. It was like they were good actors paid to get the timing right and who took pride in doing their jobs better than anyone else. When Sam had been unconscious, Dean had been skirting the conversation lamely. Several questions went unspoken and unanswered because Sam usually asked them and Dean didn't want to interrogate without his little brother.

But now Dean was a vision of self-confidence concerning Kathryn. Arrogance and his playful rudeness were ever present before Sam's woken eyes. There was even a difference in posture, a lean towards his brother, a head casually lilted away, knelt down so he could push in front to protect Sam if need be.

Sam seemed casual in a 'where's-the-monster-that-lives-here?' sort of way. His hazel eyes had been darting constantly, taking in everything. His posture was stiff, ready to leap into action if the need arose. But when Kat had said her father was an Angel, there was a different sort of guarding. His shoulders subconsciously, very slightly, rolled forward, just enough for her to notice, guarding something deeper than a heart or a lung. Guarding something worth so much more.

All of these things Kat took in with a blink and the start of a breath. Then time started again and the men were recovering… if that was the word. Dean wasn't blinking or breathing. Sam gulped, tilted his head in confusion and gave her a carefully questioning glance, as if he had heard wrong. 'Aww, that's so cute,' Kat thought. His face cleared and Dean blinked out of his reverie. Sam was the first to regain his voice.

"Your father's an Angel?" he asked.

She nodded. The brothers exchanged a glance. "He came for me about a year ago on my birthday, telling me what I was. He was so happy to see me." She grinned, remembering it.

"Anyways," she continued after a moment. "He told me he could always hear me singing and he would always come when I sang. We all three need out, so I figured it would be a good time to call." She paused, waiting for questions. Sam took advantage of the silence.

"Would you mind if Dean and I talked in private?" he asked. He cast a glance at Dean.

"Go ahead," the woman answered. "I'll keep calling." She stood, turned, and went to grip the bars of the cage. Her voice rang out sweetly in the rank of the sewer.

"I've heard there was a secret chord
That David played, and it pleased the Lord
But you don't really care for music, do you?"

Sam hadn't realized he was in pain until the pain was suddenly gone. Even Dean seemed to feel the lessening as they stood and paced to the other end of the cage.

"It goes like this
The fourth, the fifth
The minor fall, the major lift
The baffled king composing Hallelujah

Hallelujah, Hallelujah
Hallelujah, Hallelujah"

Dean's whisper broke Sam away from Kat's voice. He snapped back to reality. Relieved to see that he wasn't the only one distracted so plainly by the beautiful song, he asked Dean to repeat himself. "What?" he asked foggily.

Dean's eyes were unfocused and glazed. "Uh," the older brother mumbled, rubbing his eyes. The bandage above his eye fell off. Where there had been a gash, there was now only a tiny scratch. "Right, sorry. So do you think she's really part Angel?"

Sam glanced at her. He didn't have a doubt. She was at least half Angel. Her voice, her face, the way she walked and moved, there was no way she couldn't be at least half. Aloud he said, "I don't know." Dean gave him a look that said, 'Bitch, tell the truth.' "There are stories about half human-half Angel beings. They're called Nephilim."

"I thought Nephilim were supposed to be giants or something?" Dean muttered, blinking in and out of the haze falling over them. He turned to Kat and growled, "Could you sing a little quieter please?" She did, and it didn't work at all. If anything, the haze grew thicker. "She's obviously not a giant."

"It also says they're the children of fallen Angels and men," Sam said. "The question is, which fallen Angel is it?"

"I don't know," Dean muttered. Sam glanced over at Kat as she sang. Her voice changed pitch with ease as she started over.

"Should we tell her?" Sam asked.

"Tell her what?"

Sam shook his head to try and empty it of the fog. "That she's not the daughter of an Angel." His voice seemed disjointed from his mouth and his speech slurred heavily.

"No, Sammy." Dean sounded high. "She'll stop singing."

Sam fought the trance as it fell more heavily on him. He walked over and shakily tapped her shoulder. Kat turned to him and smiled, holding the note longer and sweeter than ever. Her voice aimed at him was too much. He stumbled toward those eyes, glowing aquamarine in the dark, towards that beautiful smile. She caught him as he stumbled into her. She looked concerned.

"Sam, are you okay?" she asked, worried.

His breath caught in his throat. He was never surer he was lying when he said, "You're not the daughter of an Angel." She stopped smiling. It felt like she had punched him. The trance fell away with a silent thud and a… slither? That was why she wasn't smiling. She tugged Sam to the ground and ran to Dean, pulling him over and shoving him down beside his brother. She slipped between them, staring up between the slats of the grate. Up close she smelled like candy flowers. Sam turned his eyes where hers were aimed.

The slithering was sickening, moving above them. He could see the ceiling over 10 feet above the slats, but not see anything making the noise. He strained his eyes.

"Don't bother," she said. Her voice was cold. Her face was set in stone.

"What is it?" Dean asked. She hissed for him to be quiet. The slithering was moving away down the sewer. The silence was tense. Sam could hear her breathing was ragged. She was afraid. Sam moved a tiny bit closer to her. His shirt by his belly brushed the jacket still tied around her waist. When the last echoes of the creature had faded into silence, Kathryn allowed them to quietly sit up. Sam didn't move away.

"Please tell me neither of you saw it," she begged, closing her eyes.

"No," Dean answered for both brothers. She sighed in relief.

"Good," she breathed. "That was a basilisk."

"What the hell is a basilisk?" Dean asked.

"An ancient breed of snake," Kat replied.

"Like from Harry Potter?" Sam asked. Dean turned and stared at him, frowning. Sam deliberately didn't meet his eyes.

"Sort of," she said, not noticing Dean's disappointment in Sam's geekiness. "You know how in Harry Potter if you look at it you're supposed to die?" Sam nodded. "Well, that's how it is in real life, only you can only see it if it's hunting you. That's your only warning that you're going to die. They never fail at a hunt."

"We were here after disappearances once every-"

"Twenty years over the past hundred, yes," Kat interrupted. "That's whenever they can eat. Once every twenty years. This one's due for a meal."

"So what, we're next?" Dean asked.

"What did I just tell you?" she snapped. "None of us could see it, so we're all safe. Plus they don't raise their meals beforehand. We're a trap for someone."

"Who?"

She stared back at Sam without blinking. "My dad."

The brothers stared. "How long have you known?" Dean demanded furiously. "You were willing to let an Angel die to get us out?"

"I only just found out when you guys said you couldn't see it," Kathryn snarled. "Calm your tits!" Sam snorted loudly and looked away from Dean. He could feel his brother's furious gaze burning into him, but he didn't care. This girl was talking to Dean as if she was Dean. A short, blond, skinny, woman version of Dean, but all the same.

Dean was silent for a moment. Then he spoke. "Well, little Miss Angel," he snorted. "How do we kill it?"

"We don't."

"Drive it away?" he questioned hopefully.

"As far as I can tell, salt doesn't work," she replied. "Weasels do. And if a rooster crows they're supposed to die. But this works just as well." She pulled out a long silver blade. Sam breathed in sharply. "An Angel blade." It looked just like Castiel's. "This could kill it, but we would have to be able to see it."

"So how do we kill something we can't see?" Dean asked.

"We don't."

"I'm already sick of you saying that about killing things."

"Shut up, Dean," Kat growled. "If Dad gets here and zaps us out fast enough, it'll be okay and he won't get killed. Some other Angel can get it. Besides-" She snorted. "-he's wearing some guy to the prom. If the dress falls off, that stupid snake gets the full fury of a naked Angel. It won't survive that."

"You're willing to risk your own father for this?" Dean asked quietly.

"He's an Angel, he can just pop back to Heaven and wait for a new vessel," she said. "Besides, whoever's doing this is either trying to kill Angels and doesn't know how, or are trying to kill basilisks and do."

"You think somebody's controlling it?" Sam asked. She simply pointed to a symbol painted on the wall. It was written in dark, dripping- "Is that blood?"

"The blood of a lamb," she assured. "Used in a basilisk binding spell. Whoever made it is controlling this thing and forcing it to go after certain targets."

"How strong is the spell?" Dean asked.

"Imagine trying to walk a whale on a piece of twine up a mountain in the snow," Kat said, thoughtfully cheerful. "Not that hard."

"I really hope you're being sarcastic." Dean was not amused.

"I don't know exactly how well it will hold," she continued realistically. "I didn't see the ceremony and I'm not very good at sensing power yet. It's above petty little charms like this-" she tugged on her Anasazi pendant. "-but other than that, I can't tell."

"Why do you wear that one anyways?" Dean snapped. "It only deflects Windigos."

"I'm afraid of Windigos," she replied calmly, gracing him with a look that said, 'you dumbass.' "Problem?" She raised an eyebrow. Dean shook his head and looked away. Sam looked at her and playfully returned the look she had given Dean, smiling. She grinned.

"Okay, so what do we do now?" Sam asked.

"You two stay quiet," she replied. She tucked her head down, closing her eyes and facing her lap. Her pink lips wiggled a bit as she mouthed a prayer. Then she stood up, paced around, looking above them carefully. She stopped and stared. A pinhole of moonlight shone down from the ceiling. "Maybe he'll hear my favorite chords," she murmured half to herself. Her mouth opened and Sam was captured again.

Maybe there's a God above
But all I've ever learned from love
Was how to shoot at someone who outdrew you
It's not a cry you can hear at night
It's not somebody who has seen the light
It's a cold and it's a broken Hallelujah

Hallelujah, Hallelujah
Hallelujah, Hallelujah

She grit her teeth for a moment. "Second favorite next," she muttered over her shoulder. She was clearly very frustrated. She began anew.

Your faith was strong but you needed proof
You saw her bathing on the roof
Her beauty in the moonlight overthrew you

Sam could feel the passion in her words, could feel her singing straight to him about her. His heart thrummed in his chest.

She tied you to a kitchen chair
She broke your throne, and she cut your hair
And from your lips she drew the Hallelujah

Hallelujah, Hallelujah
Hallelujah, Hallelujah

Kathryn's voice rang out, sweet and loud. It ricocheted around the sewer, vibrating the thick air. Her passion seeped into Sam's bones. He could tell she was getting desperate. She gripped the bars tight and looked at her feet. "Come on, Father, please," she begged under her breath. "I never sing this one. I saved my favorite for you." She looked up. Sam could see the desperation burning in her eyes as she stared at the pinhole of moonlight. Her hunger was evident in every note and vibration in her favorite verse.

There was a time when you let me know

Her face clouded with frustration.

What's really going on below
But now you never show it to me, do you?

She looked down again, and the hurt of betrayal flowed off her in waves. Her voice gradually grew louder with the next few lines.

And remember when I moved in you

She threw her head back and sung her heart out.

The holy dove was moving too
And every breath we drew was Hallelujah

Kat held the note until her voice broke. A better word would have been 'shattered.' It tore itself out of her throat. It smashed itself against the walls until it faded away. She gripped the bars and faced dead ahead. She could feel Sam and Dean's eyes on her, burning holes in her flesh. 'Look away,' she begged silently, throat and eyes burning. 'Look away before I break.' She still hadn't made a move or a noise.

She slowly lowered her face so she was facing the ground again. Her knuckles went white. Her shoulders shook. She was trembling. She fought to control her breathing. Suddenly she spun and burst out.

"Dammit, Dad!" Her voice slammed against the ceiling as she screamed. Sam and Dean jumped.

"Shh," Sam hissed. She ignored him.

"Where are you? I'm right here! Not exactly hard to find!" She was fuming, hot, angry tears threatening the verge. "I waited! I waited for you! I saved my voice for you and you left me!" She threw her arms open and faced the sky. "Come find me, you bastard!" Kat let her arms down but tried pushing her voice louder. It shattered again, but she still pushed. "Help us!" Silence answered her. Sam and Dean were holding their breath. Just as the tears were about to spill over, she heard a voice in her head.

'If you know my name, I will come,' it whispered. A light burst in the back of her mind. A name was whispered in her head. She looked up again.

"Castiel," she cried. The name felt foreign on her tongue, but it felt good somehow. "Castiel, I need you!" She heard the rustling of wings behind her.

"Kathryn," a familiar, scruffy voice said. She spun around.

"Daddy," Kat cried. She fell into his arms, sobbing. His trench coat enveloped her in his embrace. His stubbly cheek rested against her forehead and his dark, curly hair cast a shadow over her face. Her tears spilled easily down her cheeks onto his blue tie and white dress shirt. She sobbed heavily against his chest. "How could you leave me alone?" she sobbed.

"Kathryn, I'm sorry," Castiel replied. His arms were still wrapped around her as he nudged her chin up to face him. His cerulean eyes met her aquamarine ones. "You had to learn my name on your own."

"Why?" she asked, burying her face in his shirt. More tears slipped down her cheeks.

"I needed to know when your training was ready for the next step." He half smiled reassuringly. "You can sing any time you want now. I will come when you pray." He hugged her tightly to him. "By the way," he whispered in her ear. "We need to work on directing your voice. You drugged both of them when you were only trying to impress Sam with your voice." His eyes were full of mischief. Kat laughed shortly and buried her face in his shirt again.

When she opened her eyes, they were in a subway tunnel emerging into early morning sunlight. A black '67 Chevy Impala was parked in front of them. Dean grinned and jogged up to it and ran his hands over the hood. "Hey, baby," he purred. "Did you miss me? 'Cause I missed you!"

"We are out of the range of the basilisk," Castiel said. "I transported the car here. We are now in New York City. Another Angel will be sent to kill the basilisk. Angels can always see them. Kathryn couldn't see it because of her human blood."

"She better not have any dents in her," Dean snapped over his shoulder. His eyes were glowing happily as he looked at his car. Kat laughed shortly and smiled at him.

"Nice car," she said. Dean looked back at her, grinning.

"Not as nice as you'll think yours is," Cas said. A pair of keys was suddenly dangled in front of her face. The symbol on the chain was a running horse.

She screeched. "What?" she cried, now grinning. "No way!" Castiel nodded forward. A Mustang was parked in front of the Impala. It was a black '69 Fastback with clay red racing stripes and air intakes on the hood. The chrome shone brightly in the early morning sunlight. She squeaked, grabbed the keys, and ran to the car. "Thanks, Dad! It's gorgeous, I love it!"

"The trunk," Cas ordered. Kat raced to open it and found an arsenal. Several sawed-off shotguns were scattered around in a hidden compartment beneath the actual trunk. There were several Angel blades, a few knives of silver, bronze, iron, and regular steel. A few stakes of different kinds of wood were littered throughout the trunk. Silver, iron, and salt shotgun rounds were stacked in neatly labeled boxes. A few boxes of silver and regular bullets were pinned by a huge book. The book was leather bound and old. About ten other books like it were scattered throughout the trunk. A small wooden box was on the far right side of the trunk. She opened it and grinned.

"FBI, Park Ranger, Police Officer, college student," she listed off the types of IDs she now had. "Thanks, Dad!"

"Hey," Dean called from the passenger side of the Mustang. "Beer." He pulled out three cans from a small cooler on the passenger side.

"Gimme," Kat cried, grasping at one playfully. Dean grinned and raised the can over his head. She took the one from his other hand instead. He laughed. Castiel was the only one who didn't drink one. Sam and Dean leaned on the hood of the Impala while Kat and Cas stood against the now-closed trunk of the Mustang.

"So, Cas," Dean said, opening his beer. Kat gave her father a confused look.

"I know them," he explained briefly. She nodded and took a drink.

"You never told us you had a kid," Sam said. Dean grinned.

"Who's the baby mama?" Dean asked mischievously. Castiel tipped his head to the side, confused.

"Castiel said that he combined his DNA with that of both of my parents," Kathryn replied for him. "He's like daddy number two for me."

"So you're basically a science fair project?" Dean asked. She felt a slight twinge of annoyance.

"I was touched by an Angel and borne by a human," she smarted. "I'm a Nephilim, not a test-tube baby." She saw Sam flash his brother a smug glance. She bit back a smile and turned to the Angel. "So what's this about me knowing your name?" Castiel took a deep breath.

"From the moment you met me, an invisible bond has been forming," he said in his husky voice. "A mental bond lapsing over anything: space, time, nothing affects it. When you knew the most basic information about me without being told, I knew the bond was ready for molding." His gaze had slowly grown sober and tense. "You will soon begin a new form of training."

Kat nodded, rolling her shoulders back slightly and feeling the muscles move fluidly. At first it had been information about the supernatural, which she already knew a lot about. Then physical conditioning. She was now smart, fast, strong, and what other people called 'gifted' with a weapon. Kat called it lucky. "I'm ready," she assured. Castiel didn't flinch. Kathryn felt the need to.

"Don't assume," he growled. His brow furrowed with worry. Suddenly Kat felt more like him than ever. She felt ancient and tired. "Go back to Phoenix." She nodded, tossing her empty can into the back seat and getting into the car. She saw Castiel stand back with the brothers as the engine roared to life beneath the black and clay red hood. She pulled away and pointed the car west. Sam waved at her from the rearview. She wondered if she would ever see him again.

"Cas, what's wrong?" Dean asked as they watched the car fade into the distance.

"She's not ready," Castiel fretted in a monotone voice. Sam stared after her, wishing he could hear her sing again and wondering if he ever would. He snapped out of it when Cas spoke again. "Imagine the worst job you've ever been on. Your worst days, worst injuries tripled and tossed onto her like it's nothing. If she doesn't do well in this form of training…" He looked over at Sam. His heart went cold. "She could be destroyed completely.