"I can help you to become good."
For her it wasn't just a sentence. It was a promise Jack Kline made.
3 weeks passed quickly and the two young people got closer & closer.
But everything has an end.

"You can't just leave the pancakes in the pan!", Jack shouted and went into the livingroom where Y/N was sitting. "Oh can't I?", she said, laid down the newspaper and looked into the pan to find a burnt pancake. "I'm sorry.", she said and shrugged. Jack smiled slightly. "It's okay. These were your first pancakes.", he said and went back into the kitchen to get rid of the burnt pancakes. When Jack went back into the livingroom Y/N said:"I think I found something..."
Jack nodded and called for the Winchesters. She handed them the newspaper and Jack turned on his computer.
"Is this really how it's gonna go forever? I do research for cases, you do research on what I found, then Sammy and Dean-o find these monsters and kill them. Meanwhile Jack and I are bored to death?", she said while standing up and walking into their direction. "I'm sorry, Y/N. It's just too dangerous.", Sam said and looked at her. "But this time it's gonna be different. We need to take Jack with us.", Dean said and got up. "So I'm gonna be bored all on my own?", she sighed and looked at her best friend Jack to say something. He just smiled slightly at her and whispered:"I'm sorry."
"That's exactly what you're gonna do. And you could clean up the dishes.", Dean said and walked away. With a sigh she crossed her arms and looked at the two other boys. But they walked away as well, monsters didn't wait.

She went into the kitchen where the dishes were waiting for and started to clean them up.

Y/N's POV

When I heard the door getting locked I turned around. They knew me well enough, was that really necessary? Even though it was the first time ever that I was alone, this was just not necessary. I sighed and continued my work.
Cleaning the dishes
What in hell's name was that even? I was  HIS daughter, almighty Lucifer's daugther. And this was I was doing? Did the Winchesters even like me or was I just a pet to them.
I accidentally dropped one of the dishes and it shattered into thousands of pieces. "DAMN IT!", I shouted and tried to pick some of it up. But I cut myself.

Looking at my healing cut made me realize what I was. Who I was. What I was supposed to do. I turned off the water and walked out till I was standing in front of the locked door. With a smooth move I opened it and started smirking.
This was who I was.

JACK'S POV
Dean gave me the small lighter. "Do it.", he said and I nodded. I took a breath and throw the lighter into the hole we had just digged. The bones did instantly catch fire. Sam picked up the shovels and brought them to the car, Dean opened a beer and started drinking it. But I just stared into the flames. I was regretting leaving Y/N at home. When we left she looked so sad. I didn't like seeing her like this. She deserved better. I bit my lip at my thought. Why did I even care so much about her?
Maybe it was because we were best friends. But maybe it was because it was more than that.
"Are you coming, Jack?", I heard a voice saying. I turned around and looked at Dean and nodded. Both of us got into the car where Sam was waiting for us. Dean started the engine and we left the place.

The three of us drove for a few minutes when I noticed something. "The grave.", I said and turned around hysterically. Dean stopped car. "What's wrong?", Sam said. "I left my jacket. It's the last thing my mom got me.", I said and looked at the two brothers. "We got this.", Sam reassured me and Dean turned the car. We drove back to the graveyard.
When we arrived me and Sam got out of the car. A bright, yellow light was glowing from where the grave once was. "What is that.", I whispered. Dean got an angel blade out of the trunk, he handed Sam the demon knife. "Stay behind.", Dean said and nodded at me. I did what he told me to.
Suddenly the light went off. Dean and Sam took the chance to get closer. "Don't.", a familiar voice said. "I'm going to kill you if you get any closer.", the voice said again. "Son of a bitch.", Dean mumbled and got his gun out. He aimed at the direction where the voice was coming from. "You can't kill me.", the voice said and laughed. "What is going on.", I said and got closer to Dean and Sam. "I told you to stay back.", Dean said and I bit my lip. "Is that you?"
"Is that you, Y/N?", I asked again and it got silent. I could finally see her petite frame walking towards us. She looked just like her mother. "You underestimated me. All the time.", she said with a broken voice. I wanted to take a step forward but Sam stopped me. "But I realized that I am not like you. And I will never be. So it was probably better like this.", she said. Her voice was cold, dangerous and it made me shiver. "You are one of us.", I whispered. "We didn't leave you behind because we think you were not strong enough.", I said and looked at Sam. He nodded and got his arm out of my way so I could walk towards her. "I was scared.", I said and took my last step. We were staring into each others eyes. Only a few inches away from each other. "I was scared that they'd hurt you. After I lost my mother I got overprotective, over the people that I love. And I surely love you, Y/N.", I said and rested a hand on her shoulder like I did the first time that we met.
Her reaction was unforeseeable. She was so different from when we left. Her whole aura was so much more dangerous and could. "I love you.", I repeated. "I'm not gonna leave you. None of us.", I said and looked over my shoulder. Sam and Dean were nodding at us. "Just let me help you.", I grabbed her tightly. She kept staring at me before she fell into my arms and started sobbing. "I'm sorry. I was just so angry at you for leaving me behind. I thought you were thinking that I was too weak and not able to fight.", she mumbled and pressed her head into my chest. I hugged her tightly. "It's gonna be okay.", I said.

But I was sure it wasn't.

A/N: I know Jack is slightly different from how he is in the show. But in my AU Jack isn't a nephilim, he grew up like a normal human :) So I think his personality would be a bit different from the SPN version.