Author's Note: This fanfiction is based off of a fanmade video on YouTube called Kuroshitsuji Black Butler Sebastian & Ciel Kokoro Fanmade Vocaloid AMV by MakenshiCronaGorgon, who came up with the story plot in the description, where she wrote the summary. So, all rights go to her work and the song Kokoro by Rin Kagamine. So please do go check out her video and listen to the song, if you have the time to do so. Thank you.

Disclaimer: I do not own anything except for my own writing. Characters belong to Yana Toboso and story plot goes to the people listed above.

Warnings: Character death, OOC, unbetaed.

"S-Sebastian...p-promise me one thing…" My master chokes out, despite the little time that he had left in this world.

I do not hesitate to answer, for I would be his faithful butler until the end, as the contract stated. "Yes, my lord?"

He looks at me straight in the eye with his one sapphire orb. "K-Keep my family ring...never destroy it or let it be ta-taken away from-" His face twists in agony as he doubles over the stone bench and retches out blood before sitting up and continuing. "Y-You… just treasure it… and protect it as you did with m-me…"

I do not understand why he asks me of this, but, I agree to it anyways. "For you to give a mere servant a precious ring is an honor, young master. I will protect it with my life." I promise him as he shakily removes the ring from his thumb and places it in my hand. For some strange reason, it felt surprisingly warm, as if there was something inside of it. I dismiss the thought soon after and pocketed the ring, returning my attention to the child sitting in front of me.

"Are you ready now, young master?" I ask him, slowly slipping off the glove, revealing my contracted hand and symbol. My eyes glow a light violet as he slowly nods. "Well then, young master...this is goodbye." I say before leaning in and scooping his body into my arms.

He closes his eyes and take it as a sign to begin. My lips found his soft ones and I molded his inexperienced lips against mine. My tongue slips into his hot cavern as he immediately granted entrance and I find that delicious soul of his, eagerly feasting upon it until there was just a little speck of it left. Then that speck was gone, and I slowly pulled back, the last spark of life within the boy slowly disappearing.

"I love you…" The boy whispered to me with his last breath of life.

My former master's body lay limp in my arms, the last of his soul and essence sucked out of his fragile body. His soul tasted sweet, perfect, and absolutely scrumptious. It was more than I had ever imagined.

I did not react when he told me he loved me. I was confused, to be exact. What is love? How could he have possibly expected I, an unfeeling demon from Hell, to know what that meant? The demon race could not feel human emotions. I did not feel anything when I killed my master.

Except for raw hunger. That was all.

I decided to bury my master properly, since that was what humans did these days for the rich and nobles. With an monotone expression, I took his body into my arms and placed him into a coffin that I had made just for him. It was decorated black and white, a few white rose petals inside as I lowered him gently into the small space.

I do not know exactly why, but I wanted to preserve at least his body. After all, what kind of butler would I be if I left my former master's body to rot into nothing but a mere skeleton? With skilled practice, I slid my glove off and bit my finger, drawing the demonic blood out from my body. I opened the boy's mouth slightly and let my blood drip into the slowly drying cavern. A demon's blood will let a human body stay as it was eternally before they died.

Once finished with the task, I arranged his body so that it looked professional, like he was a porcelain doll that I was dressing up and playing with.

His eyes were closed and his hands rested on his stomach, entwined together. He looked as if he was sleeping. I stare at him for a while longer before I took the lid and slowly covered it, sealing the remains of Ciel Phantomhive inside of the coffin. "Goodbye, young master." I whispered monotonously.

I took the coffin and carried it back to the Phantomhive manor, where he told me he wished to be buried. I, as his faithful servant, went through with his orders until the end and buried him into the Earth, right in the Phantomhive rose garden. My master was always fond of roses. I did not know what it was like to be fond of something, but perhaps he was the closest thing of me being 'fond' of something.

I dust my gloves off when I was done with the burial and stared at the completed gravestone.

Ciel Phantomhive

Died 13 Years of Age

December 14, 1875 ~ December 14, 1888

It was such a shame that everything unfortunate happened on his birthday. Including his own death. Yet, I did not feel any remorse, or whatever it was humans felt when someone close to them died.

Human emotions. They were nothing but mysteries to us demons. We were created to eat souls. We were made from the darkest pits and evils of Hell itself and rose from the flames to cause pain to the humans. Why that is, we do not know. So, I had concluded that they were nothing but useless 'feelings' that humans had that caused them to be so fragile and weak. To protect another living being with their own lives because of emotions was foolish.

With the last words of Ciel Phantomhive ringing in my ears, I stepped back, bowed dutifully one last time as the Phantomhive butler, and walked away from the grave, where the body Ciel Phantomhive rested. I did not look back nor did I ever think of him again that time as I went to search for a new master.

=KoコKoコRoロ=

I walk into the streets of the busy London, scanning the large crowd of people. Every soul here was imperfect, unlike my last former master's, which was perfect beyond words. Some were too shabby, some too sweet and some too salty. Maybe some spicy ones as well. None in particular caught my attention.

I strolled down the familiar street casually, until I came to a stop in front of a building entitled, 'The Undertaker'. Truth be told, I really had nothing to do in the new free time that I had in my hands, so maybe a little leisurely chat with a grim reaper might pass some time. Not that I did want to associate myself with that wonker of a reaper. But, seeing as I had been bored out of my mind as of late, I entered the shop.

A coffin opened and a familiar 'He, he, he' was heard as the Undertaker himself stepped out of his coffin. "Well, well, well. If it isn't the boy's butler. He, he, he. What can I do for you?"

I clear my throat and correct him. "I am no longer a butler of the Phantomhives. Every single one of them are no longer walking on the surface of Earth. I just came for a small chat, if you have some spare time."

The death reaper doubles over with laughter, his longer fingernails scraping the coffin as he held onto it for support. "Ehehe! You really know how to make others laugh, demon!" He chuckles when he is finished with his sudden outburst of giggles. "A chat, you say?"

I raise my eyebrow and reluctantly nod.

Undertaker seated himself in a chair and pats his hand on the sofa. I take a seat across from him.

"So, what did you want to chat about, Mr. Demon?" He asks me, grabbing a cup of biscuits and offers me some while he chews on one.

"No, thank you." I politely decline, dismissing the biscuits. "I was wondering if you know of any particular humans that might have an edible yet tasty soul?"

He goes into another round of laughter before answering. "Oh, moving on so soon? Have you already forgotten about that Earl already?"

"Well, why should I remember? He was another soul that I had devoured. Another master that I had served and taken away his life. What more do I have to remember about him?" I question, not quite understanding what the reaper was trying to hint at. That was all. Ciel Phantomhive - another human that died by my hands. What else was there to remember?

He gulps down his tea and places the cup (which was a measuring cup, mind you) onto the table and he smiles in a discomforting way. Well, his smiles were never comforting...if anything, they would make you feel like he would 'sexually jump' someone. "Is that all you think of that boy, demon? Tragic, very tragic. How unfortunate for that kid, he, he, he."

I tilt my head, not quite understanding. "Yes, that is indeed my thoughts about the boy. Why are we discussing him when you have not yet answered my last question?" I ask a bit impatiently. Maybe he was just trying to get under my skin, but I would not give the reaper the satisfaction of having upset a demon such as myself.

"Let's just say...the boy had an unhealthy feeling of attraction towards you. But it looks like it was just one-sided! Ke, ke, ke...Interesting, very interesting!"

With those words, I felt something inside of my chest pocket throb. I look down, startled, as I slipped my hand into the pocket and pulled out a deep blue ring. It was glowing a light blue for some reason, and it felt very hot, burning through my gloves and coming in contact with my skin. It did not affect me one bit, heat wasn't enough to hurt a demon. Though, it was strange. Since when did the young master's ring glow and burn?

I felt another throb deep within the ring as I examined it curiously. A pulse? In a ring, of all things? My eyebrows knitted together as I tried to recall a memory of the ring having mysterious powers of some sort, but remembered none. Just what was going on?

"Ah, so he gave you his ring. Such a neat reaction from it with the truth coming from your own lips, Mr Former Butler!" Undertaker said with another unnecessary giggle.

Truth? What truth? "...Undertaker. Do you know something that I do not know about?"

To my surprise, his answer is a strange one when he tells me this: "Yes, I do. You might understand, demon, if you slip on the ring onto your finger.~"

I am cautious when he told me that. To tell someone to put on a ring that felt like it was alive and burning was practically what the Undertaker would say. It made me wonder what on Earth this stupid reaper knew that I did not. Even so, I had long known that he was trustworthy. To some extent, as far as I knew.

He smiles wider, showing off his yellow-white teeth and urged me to go on.

I was reluctant and hesitant at first, keeping my guard up in case I would be in any kind of danger once this ring, once the young master's ring, was on my finger. But I finally did it-I slipped the delicate piece of jewelry onto my finger and it burned off around my finger through my glove.

I brace myself for any kind of danger that might occur - but after a few seconds of waiting, nothing happens. I could hear the Undertaker laughing hysterically in the background while I stared at him with a confused expression on my face, clearly not amused.

"Nothing happened." I stated with fire in my eyes as I watched the immortal being enjoy himself for tricking a demon, and I was not going to let him off of the hook. He continued to laugh like a hyena as I stood up abruptly and began to reach out and grab him by the neck, but then it happened.

Bump, badump. Bump, badump…

I suddenly feel dizzy as my head starts to pound. No...it wasn't my head...it was…

I tentatively placed my hand over my left chest, and I felt it. Something strange, something...unexplainable was beating inside of my body. I was overwhelmed with memories of Ciel, and a strong...what was it? A strong feeling - it made my eyes water and I stood there, shocked. I touched my face and I felt that it was wet.

Tears. Tears were running down and dripping onto the ground. My tears. What was going on? I am a demon, yet I am crying.

"Hey, Sebastian. Tell me what you think of this dress." My young master spins around, his pink dress flowing around him as he smiles. I do not return the smile.

"It is for a lady, young master." I answer plainly, a frown on my face.

A look of...what was it? Disappointment, I decide, crossed his face for a moment. "I see...yes, that's right. I have to dress up as a lady for the Viscount Druitt's party, after all…" He said quietly, still staring at me, as if wondering if I was going to continue saying something.

I did not. What else was there to say?

He sighed and began to slowly walk out of the room, closing the door behind him, leaving me to prepare for the ball.

I did not understand the sudden change in my master.

Why, why won't my tears stop flowing? Why am I shaking? What are these beats inside of me?

I heard Undertaker chuckle. "Congratulations, demon. You now know what no other demon has known or discovered - human emotions. You have a human heart."

...A human...heart?

The words felt foreign to me. A human heart.

"...How?" I manage to ask despite the strange emotions that were coursing through my body.

"It's quite simple, really. He, he, he. One day, your little master came to me and asked me a favor - to let all of his feelings be sealed inside that simple ring. In other words, heart transfer. I felt a tad bit bad for the young lad, so I gave him my services for free. All I did was inject him with a potion that would transport his feelings for you - his heart - into the ring when his time is almost over. Now you can feel, can't you? The boy's feelings for you. His memories of you." Undertaker explained casually while he leaned back into his chair. "His heart is beating inside of you."

My young master's…heart? Inside of me…?

"Young master…" I say out loud. I hear his words echo in my mind, and I feel like I will break.

"I love you, I love you, I love you…"

My heart was aching. Like it was broken in pieces.

What did I do to my young master?

I killed him.

I killed my young master.

Please stop, young master…

He doesn't. "I love you, I love you, I love you…Sebastian…"

It is embarrassing, for a demon to show such strong emotions in front of others, much less the Undertaker. But I couldn't stop the tears from flowing. Tell me, how does oneself stop crying once you start?

My body is trembling and I can't stop it. My former master's heart and feelings for me - they are inside of me, beating, pulsing…

Badump, bump…

"What do you think of this-" My master sneezes. I am by his side immediately, checking for any signs of illness. He isn't sick in any way.

"Stop it, Sebastian. I'm-" Achoo. Another sneeze. I frown. "I'm just allergic to- cats...But I thought you might like it." He is sniffling now, a black cat in his arms as he holds it out to me.

I take the creature from his hands, unfazed by its looks. "Thank you, young master. For you to do such a thing for a mere servant like me is very flattering." I say that, but my words are not true. What is appreciation? Flattery? I do not know. I am a demon.

His eye radiates with...happiness? "I'm glad you like it, Sebastian."

I nod curtly and let the creature down, and it runs out of the door. My master frowns at my action.

"Why did you let it go? I thought you'd like it…"

I am confused. "Why would I like cats, young master?"

He shakes his head, eye focused on the ground as he sneezes again. "Never mind…"

Young master...my lord…my Ciel…

The human emotions are overwhelming and I found that I couldn't stand anymore. I plopped myself onto the couch and sit there, memories and feelings taking over my body.

The Undertaker doesn't say or do a thing, simply observes me, watches me.

I am sorry. I am at fault. I shouldn't have killed you, Ciel.

"I love you, I love you, I love you..."

My tears continue to fall endlessly.

Young master...

I want to see you...

That was when I stood up abruptly, slammed open the door, and walked out into the blinding light of the sun.

Author's Note: To be continued. Please review, follow, and favorite. That'd be appreciated, thanks. Also, ココロ spells Kokoro in Japanese letters.

Signed, M.S.