Plot: you didn't tell Dean that you had the Mark of Cain one day because of amara and you went on a hunt then the mark pulled the blade to you and you kill the demons.
Your POV
I splashed water over my face and sighed. I looked back up at the mirror and wiped my face dry. I looked at the mark, the mark. Amara gave it to me, a lock and key for the old cage but this time, the cage is locking up the whole purgatory. If I remove the mark, Leviathans roam earth free again. The blade was in the bunker and I try my best not to look, see or even touch it. I slammed my arm down at the edge of the sink and grunted. I looked at the mark and at caused my hand to shake uncontrollably. I didn't mid it and headed back to my room, I walked past Sam and pulled down my sleeve. He doesn't know about the mark. "Hey (y/n)," he said then I stopped tensing my whole body. "Hey S-Sam," I waved then ran back to my room. I closed it, sighed in relief and slid my back down on the door sitting down on the floor. "(Y/n), why do you have Amara's mark?" He asked sitting down on my bed. "Cas quiet down!" I whispered loudly at Cas.
"My apologies. But why do you have it?"
"Because Amara said that Chuck made the cage bigger and it locked the whole Purgatory. All of the souls are trapped. It also included of my will of hell. I can kill anyone Castiel. Anyone. That's why I became a better hunter than I was before. I'm immune to any demon powers,"
"(Y/n), you do know that Dean will find this out soon right?"
"Castiel, if he does, let him know. But not now,"
--
"So get this, the demons are possessing everyone,"
"It ain't a news flash Sam,"
"Shut up, so they possessed the sherriff but they held captive of the deputy. What does this mean?"
"They have taken hostage let's go," I said grabbing my coat which has the First blade since Castiel put it there for me and a pentagram bulleted gun. I slupped on the coat and headed put to the Impala. I sat in the front seat inbettween Sam and Dean since the back seat was full of duffle bags and Cas. Dean drove for 10 minutes and Sam knows my feelings for Dean, but Dean, I kept it for me, Sam and Cas because I don't wanna get it Dean's hookups with his chicks. I sighed at my thought and Sam looked down at me. I looked up and him and glanced at him. Then Dean stopped infront of the police station and the skies thundered. We stepped out of the car and I slid to the passenger seat to get out. I went out and slammed the door with my right hand and Dean glanced at me. I sighed deeply and looked away. "Hello boys," we heard an unfamiliar voice behind us. "And (y/n)," Lilith's brother, Jonathan a Knight of Hell nodded at me. Then demons started to appear and attack us. I need to kill Jonathan. I sneaked my way behind Jonathan while Sam and Dean fight them off. I grabbed my blade from my coat and ran behind the car. I jumped out behind Jonathan ready to stab him but he caught my wrist, gripped it tight and cause the blade to fall down. He kicked it away and turned to me. "(Y/n)!" Dean shouted. Jonathan kneed me in the stomach and I fell down. He slapped me then punched my jaw which caused me to back up. "(Y/n), you're weak," he laughed as he kicked my shin then my stomach. "Get up," he gritted. He gripped my shoulders tight and stood me up. He pushed his hand towards me and I flew all the way back. I grunted once I hit Baby and cracked the back windsheild. Jonathan walked over to me and held my shoulder tight and he smirked. A shining blade appeared in his hand and he was playing with it. I held my hand out to my side and the blade came in my hand. "Think again motherfucker," I chuckled then punched his jaw forcefully. His head twisted and I jumped on my feet. I bended down to my knees and stabbed the blade straight into his heart. He looked at me with pain in his eyes. I lifted him up witha grunt and I was standing on the trunk lifting Jonathan with the blade and he was gripping on my hand and shoulder tight. He started to glow reddish orange and the demons near us became dust. He screamed and I furrowed my brows. The light became brighter and brighten and wind was gushing all around us. He screamed once last time as he went limp and fell down. "(Y/n)?!" Dean screamed as I jumped off of the trunk. I looked down on my sleeve and pulled it up. The mark was glowing and I was hungry to kill. I stabbed Jonathan again 2 or 3 more times and blood was splattered on my face. I turned back to Sam and Dean and I was breathing heavily. "(Y/n)?" Sam asked. I limped and I felt blood trickling to my jeans. I looked at my side and Jonathan stabbed me but I didn't notice because I was handling the mark. I fell down on my knees clutching the blade and I ended up on fours. "(Y/n)! (Y/n)!!" Dean yelled as I blacked out.
I opened my eyes and sat up. I grunted because there was a sharp pain on the side of my stomach. I clutched it and ripped up my shirt. There was blood in the bandage, then I was reminded that Jonathan stabbed me. I sighed and slipped out of bed. I didn't notice that my flannel was up to my elbow then I pulled it down. I walked out of the door limping. I went to the library and leaned on the wall. "Sam," I breathed out. Sam saw me and ran over to me. I clutched my side tighter and breathed. "It's okay," Sam said whispering lifting me off the ground and to the chair in the library. He sat infont of me and looked at me.
"What?"
"How did you use the blade?"
"Uhh,"
"How did you kill Jonathan?" I heard Dean's voice behind me and twisted. I breathed out tensly and he sat next to me. Sam was grinning and leaned back to his seat. "(Y/n) why did you have the mark?!" Dean said landing his fist to the table which caused me to flinch. "Dean stop," Sam said furrowing his eyebrows.
"No Sam! Why does she have the mark?!"
"To keep Purgatory on it's place!" I yelled infrong of his face. His face softened and I furrowed my eyebrows. He cupped my cheeks and kissed me. I heard Sam whistled and I melted in the kiss. He pulled away looking into my eyes. "Why did you have the mark?" He whispered with tears glistening in his eyes. "Amara, Amara and Chuck said that they made a bigger cage to lock up Purgatory and Hell. I can control demons and cut off a gate of hell one at a time. If you remove the mark you'll open Purgatory and let Leviathans back and open the most dangerous gate to hell," I said looking down and away. "How many gates are there," he said gliding his hand over my cheek. "5, the points of a pentagram," I said whispering back. "Forget this crap for a moment because I will take you out tonight," he said kissing my nose then my forehead. He got up and walked away. "What just happened?" I said looking at Sam wierdly. He chuckled at em and I daydreamed of mine and Dean's date tonight.
