Sebastian watched his young master sleeping, his expression innocent and vulnerable in his slumber. He resisted the urge to brush Ciel's hair back from where it fell over his eyes. Even the slightest movement would no doubt disturb his master, and so Sebastian didn't move, just watching the young boy sleep, his body small and frail as he lay there on a bed far too big for his tiny frame. It had been his parents' bed, here in the master bedroom of the Phantomhive Mansion.

He frowned quietly to himself. Somehow, this small brat had become his weakness, a liability that he couldn't afford, but was equally loathe to give up. After all, he had a contract with Ciel Phantomhive. A lifetime of servitude and a quest for vengeance, in exchange for a soul that was as pure and untainted as a newborn babe's. Ciel's soul was a contradiction in and of itself; he could kill an enemy without flinching, and order Sebastian to burn a home full of poor, damaged children, and yet, miraculously, his soul remained untouched.

Over time, Sebastian had found himself growing particularly attached to his newest master. He was willing to do anything the boy asked; for the first time, he found himself doing things because he wanted to, not because he was ordered to. He had studied and learned Ciel's favorite foods – especially desserts – and prepared meals accordingly, balancing health with pleasure in every meal. He attended to his master's every need, and no doubt did more for the child than any butler ever had.

Others had noticed his attachment, though, and things had become dangerous for the both of them. All of Sebastian's efforts at cultivating this particular soul he was bound to would be for naught if the boy were to be killed. Or if another demon were to try and steal it from him, he thought, a small growl tricking from his clenched teeth.

"If you're going to just watch me sleep, then come and keep me company, Sebastian," a sleepy voice murmured. Gleaming crimson eyes stared at brilliant blue, and Sebastian smiled, moving forward until he was standing next to the bed. A small, warm hand reached up and tugged on his wrist.

Following that hand, Sebastian allowed it to guide him down, until he was seated on the side of the bed, one knee tucked under him while the other was curled over the edge of the bed, hanging loosely. It was a casual pose, one that Sebastian didn't normally allow himself, but here, in the dark of the night, it didn't matter. Here, it was just Sebastian and Ciel, demon and human rather than servant and master.

Ciel was more awake now, regarding him in that way that meant he was about to ask Sebastian to do something that the demon probably wouldn't like. He had a habit of testing Sebastian like that. Sebastian found that he really didn't mind these tests. Instead, with every one that he passed, he found himself growing fonder of the boy in his care. His young master was sadistic in his own way, but it was childish, innocent sort of cruelty, brought about more by curiosity and a need to test the boundaries with Sebastian than any true sense of maliciousness.

"Since you woke me up," Ciel began, as Sebastian hid his smile, "you are responsible for ensuring that I get enough rest. After all, I'm still growing," he scowled, and Sebastian didn't bother to hide his smile this time – Ciel wasn't growing any taller, and that fact disturbed him immensely.

The demon slipped off his shoes and crawled into the bed, so that he was tucked behind Ciel, the smaller body fitting neatly into the curve of his own. A strong arm banded around the boy's waist, pulling him back into Sebastian, so that his warmth seeped into his young master's back. He knew what Ciel wanted, and he knew that he'd give it to him – no matter how galling it was to have to admit things like this out loud. So much for his pride as a superior demon – his master managed to completely undo him, leaving him unraveled and scrambling to hide his vulnerability.

Oh, he hadn't lost that inherent cruelty that was a part of his demonic nature, but it had been softened and gentled by the affection he felt for his current master. Never before had he remained with one soul for so long. Even here, he could have simply done the research and told Ciel who his enemy was, and then promptly destroyed them, thus completing the contract and obtaining Ciel's soul for himself. But he was more than willing to allow the boy to complete his revenge at his own pace, and to let it take as long as it had to before the boy was satisfied.

Laying his head on the pillow, Sebastian kept Ciel facing away from him as he spoke. "What is it that you would ask of me, Bocchan?" he asked softly, his voice soothing and hypnotic. Ciel sighed and relaxed in his grip, and Sebastian found himself in wonder again as the boy's complete trust in him showed so plainly. Never before had any of his masters trusted him so, even knowing exactly what he was and what he wanted.

Would one who believed in God summon you? Ciel had demanded a long time ago, when he had first called Sebastian to his side. The boy could not bring himself to believe in a God that saved no one, and so instead he chose to believe in a demon that he could see and touch, and that would protect him because it was his duty to do so.

Sebastian timed his breathing and slowed his heartbeat, so that it pulsed in time with his master's. His free hand petted Ciel's hair, running gently through the soft strands, long fingers combing easily. Ciel's body relaxed further as he petted, and Sebastian smiled, leaning down and dropping a gentle kiss on top of Ciel's head. "Bocchan," he murmured affectionately.

"I promise to be yours, and only yours. I will belong to no other for as long as you shall live. I shall be your servant and your right hand. I shall be your eyes when you cannot see, and your ears when you cannot hear. I shall be your voice when you cannot speak, and your strength when you grow weak. When you need shelter, I will shield you, and when you need love, I shall love you with everything that I am."

The words were a ritual now, spoken with the power of binding. He was Ciel's, and Ciel was his. It was as simple as that. Smiling now, Sebastian continued. "I shall be your pain when you're unable to feel, and your hatred when you grow tired of fighting. I shall be your reminder when you forget your purpose. I shall always be truthful, even when it burns. If it is broken, I will fix it. If it hurts, I will heal it. If it is lost, I will find it. Everything that I am, and everything that I will be, I give to you."

His part was done now. The words, once spoken, could never be taken back. For the first time since Sebastian's creation, he had spoken the words of a demon who had bound his own soul and fate to his master's. Never before had he done so, though he had heard of a weaker demon than himself doing so occasionally. No matter what happened now, until the day came when he could finally claim Ciel's soul for his own, he was bound to his young master. He could do nothing else.

Ciel shifted in his arms, and Sebastian allowed him enough movement to roll over, pulling him back against his body once he had done so. Tilting his head back, Ciel reached up one hand and settled it over Sebastian's heart, feeling its rhythmic beat with every breath that the demon took.

He smiled softly, the smile one of affection as he stared up at the demon. Sebastian was so many things to him - a tool, a servant, a brother, a father. Oh, he'd never be able to replace Ciel's family, but he was a strong, fierce presence at his side. Ciel chuckled to himself; he had two noisy siblings in Finnian and Maylene. Bardroy was like the crazy uncle that was loud and obnoxious, but still affectionate. Tanaka was like a grandfather, enjoying his retirement surrounded by family members, watching over them with a fond sort of exasperated tolerance.

Sebastian was the only one that couldn't be easily categorized, but that was fine with Ciel. After all, Sebastian was a demon, and his purpose was to fulfill every roll that his demanded of him, no matter what. The butler watched in amusement as Ciel's eyes closed; didn't he realize that Sebastian could tell everything he was thinking when he let his guard down?

As Ciel drifted back to sleep, reassured and safe in Sebastian's arms, the demon allowed his worry and concern to show. He knew that there were others after Ciel's miraculous soul – that spider bastard Claude being one of them, with his tainted, filthy master – but Ciel was his. He'd have to be sure to keep the young master close from now on. After all, Sebastian hadn't just spouted all that sentimental nonsense just to have his contractor snatched away from him. Now that he'd said it out loud, it was inevitable; Ciel's mortal life, and immortal soul, both belonged to him. No matter what, he'd never let the boy go. Never.