You had been dating Cas for a while now and it was close to you guys one year anniversary. On a hunt a couple days ago there was an old piano in the house where the vampires you were after were hiding out. While Sam and Dean were outside burning the bodies you stayed in and started playing all of your favorite songs.

When you started playing piano man by Billy Joel, Cas had shown up behind you.

"Hello (y/n)." Said angel said putting his hands on your shoulders.

"Hey Castiel, what are you doing down here?" You said back, he was always busy in heaven and didn't have very much free time to see you.

"I heard you playing and singing so I had to come see you for myself." Cas explained putting his chin on your shoulder as you played. "Do you like this instrument?" He asked suddenly.

"Yea, I always loved playing the piano. My mom taught me how to play before I went into hunting. I wanted one in the bunker but Dean said its impossible to get one in there." You say and finish playing the song, singing softly to it.

"You are quite good at it." Cas said reaching forward and striking a few keys. "I suppose I should go back to heaven." He said kissing your cheek then standing up.

"I'll see you soon right?" You asked, turning and hugging him.

"Yes I should be able to be back by Thursday." Cas said then you heard the flapping of wings and he was gone.

For the rest of the week you were searching for something to give Castiel for your anniversary. In the end you had to ask Gabriel for help. He suggested giving Cas a piece of your soul, like a horcrux. More than anything you know that Cas wants you to be safe and with the horcrux, demons couldn't take your soul and you couldn't be killed permanently. So you allow Gabriel to put a small piece of your soul into a locket to give to Castiel.

"Ok kiddo, there you go. A piece of soul in a locket. You can always undo it if you take this back to me." Gabriel says giving you a small metal box with the necklace inside.

"Thanks Gabe." You say hugging his neck before he goes.

"Anything for you (y/n)." And with that Gabriel disappears leaving you to wrap your present.

On Thursday morning you wake up later than usual and take a shower before going into the bunkers kitchen to make breakfast. When you walk past an open part of the floor way your jaw almost hits the floor at what you see. Cas is sitting on the top of a beautiful ivory grand piano waiting for you with a bow on his chest.

"Good morning (y/n)." Cas says getting down from the piano and walking towards you.

"Hey Cas." You say still dumbfounded at the piano sitting there. You turn to start on breakfast and see Dean already beat you to it.

"Mornin' (y/n)." Dean says giving you a small wave as he flips a pancake.

"You did ask Dean if you could put a giant piano in the middle of the bunker didn't you?" You ask turning to Cas.

"Yes and Sam said it was customary to give each other gifts after a relationship had lasted a year. Dean put this bow on me and said it would be what you humans call 'romantic.' Do you like it?" Cas says tilting his head to one side.

"Yes, I love it Cas, almost as much as I love you." You say throwing your arms around the angel.

"I'm glad for that. I love you too." He says awkwardly.

You, Sam and Dean eat breakfast and afterwards you give Cas his present from you.

"You're giving me a piece of your soul?" Cas asks looking at you with wide eyes. You don't even have time to respond because Dean spits out his oj and Sam gasps.

"You gave him part of your soul! (Y/n) how could you do that!" Sam and Dean say looking very angry with you until Cas explains what a horcrux does.

"So you're like Voldemort now?" Dean asks sarcastically.

"You could say that, but if anything happens Gabriel said he would undo it for me anytime." You say shrugging your shoulders.