A/N: I'm ashamed to say this work was inspired by Rhianna's "Unfaithful" (hence the dreadful title). Apparently, music is inspiring me at the moment, and I'm taking what I can get. Sooo, here you are.

"Where are you off to so late?"

"It's not that late. I'm going out," I answered as I stood in front of the mirror, fussing over my hair.

"Yes, I'd guessed that much. Would you like to be more specific?"

"I'm going to visit a friend," I replied, sticking my tongue out at him, but he maintained his stoic attitude.

"I see. Which friend in particular, if you don't mind my asking?" As I sat on the bed to put my shoes on, I let out a sigh.

"The Undertaker. Is that specific enough?" He ignored my question for a moment, considering.

"Then…you're going to the mortal realm. To London." Something in his voice told me he wasn't exactly pleased.

"Yes. Is something wrong with that?" Again, he chose not to answer my question. "…Will?"

"No, there is nothing wrong with that." Taking my hands, he pulled me to my feet and looked into my eyes. "Should I go with you…?"

"Why? You'll just get bored; it's just girl-talk, after all, nothing you're interested in," I laughed. "Besides, I'm sure you have work to do here. You don't want to fall behind." The look on his face changed, and his gaze drifted away from mine.

"…no, I suppose not." He shook his head and stepped away from me, going to his desk. He wasn't stupid. He must have known…something.

"Will, is something wrong?" I didn't stand too close, but my hand touched his arm.

"No." But he still wouldn't look at me. "When will you be back?"

"Later tonight… You don't have to stay up or anything." He nodded but didn't look up. A few moments passed in which he sorted through the files on his desk, and I glanced at the clock. It was getting late… "I'm going to go now, okay?" I kissed his cheek and turned to leave, but he grabbed hold of my wrist to stop me.

"Wait."

"Sweetheart, I'm going to be late as it is—"

"Just wait a moment." He pulled me in close and wrapped one arm around me. His other hand slid into my hair, and he pulled me in for a slow kiss. I managed to get my arms around his neck and did my best to kiss him back. Finally, he released me. "Go ahead. I'll be waiting." I gave him a slight nod, trying to hide the waver in my smile, and then I was gone.

True to my word, I went to my friend's morgue when I left…but not for the reason I'd given Will.

"I can't say," I told him, trying to mask how stressed I was. "But if Will asks, I'm here tonight…"

"Ah, another tryst tonight, is it? Well, I can't say I entirely approve," he began. "…but then, if you can't trust a friend to lie to your loved ones, then what sort of friend are they, really? Your secret is safe with me, milady."

"Thank you," I said gratefully as I disappeared out the door and headed to my real destination. When I arrived, I let myself in, as usual, and he was there, in his bedroom.

"You're late," he informed me as I stepped inside.

"I'm sorry. I think Will is…figuring things out," I muttered fearfully.

"Is that so? And are you going to be dwelling on that all night?" Glancing up into his red eyes, I smiled.

"Not if you'll distract me." The corners of his mouth turned upward as he stepped in oh, so close and breathed against my neck. Just his soft breath was enough to make my knees weak.

"I see. Then allow me to do so." Our lips met, and as always, sparks flew. In an instant, he had me against a wall, moaning back against his lips. His hands deftly stripped my coat, and it wasn't long before his fingertips brushed my chest. Then I had to break away to gasp for breath, every cell in my body wide awake and active. Still smirking suavely, he transferred his mouth to my throat, and I whimpered in excitement. He was so passionate, every night we were together, and I couldn't resist it.

It had started weeks ago, almost by accident, when he had actually accepted my playful advances, and after all the promises I'd made, I couldn't just back down. That night, I'd gotten a taste, and I was instantly addicted. From then on, I'd found myself running back to him more and more often. I just couldn't stay away. Compared to Sebastian, poor William just wasn't enough anymore. He was caring and sweet to me, and he'd done absolutely nothing wrong, which only made me feel guiltier about sneaking off to be with Sebastian.

But not too guilty.

"Mh…" His mouth closed over a nub on my chest, and I moaned for him again, feeling my face get warmer.

"Speak to me," he purred. "You're so quiet this evening."

"S-sorry," I mumbled. "I just can't stop thinking about—"

"Oh, honestly," he said, letting me go and walking away in exasperation. "Why haven't you told him, if it bothers you so?"

"I'm going to," I protested defensively. "I just…haven't figured out how to say it yet." Of course I'd thought about it. And every time, I thought, I'll tell him tomorrow. Definitely tomorrow…

"I should think it would be very simple. Tell him that you've grown tired of his company and would rather spend your time here with me."

"It's not that easy," I answered. "There's more to it; if I just said it like that, it would break his heart." Sebastian stared at me for a moment, and his gaze hardened.

"Well, if you're that concerned for his feelings, perhaps you should go back to him and stay there; save us all the trouble of debating the matter." Suddenly irritated for some reason, I took a step closer and glared up at him.

"Is that what you want?"

"Have you considered that perhaps I don't enjoy sharing—" He paused there and laughed ruefully. "Wait. Before you snap at me, take a moment to think. Not about what I want or what he wants; think about what you want." Silence for a moment. "What do you want?" I wanted to protect William. I wanted to be with Sebastian. Which was more important…?

"I…" My words trailed off, as that thought never finished forming. Then Sebastian ran his fingers through my hair.

"Come now, you know this," he said encouragingly. "You've told me a hundred times by now." His fingers stroked down my cheek, and my breath came out in a sigh. Without the willpower to make myself stand, I fell against his chest.

"I want you," I breathed softly, desperately, and I could hear him chuckle. Entwining his fingers with mine, he took a step back and led me toward his bed.

"Then stay with me…"

Not much more was said after that; our bodies communicated on a much deeper level, voices lost in moans and muffled cries. Ever after such a short time, he seemed to know me so well, and he used that to his full advantage. I was his, any way he wanted me, and I wouldn't have dreamt of arguing. How was it that he could captivate me so fully, keep me so utterly enthralled…? I knew he didn't love me, and maybe he never would…but somehow, that didn't matter. I still craved his attention, his touch; I was falling so fast there was no chance I'd survive.

Some time later, we lay silently in his bed, our deep breathing matched, my head against his shoulder. And oh, he was holding me… And then my eyes fell on a clock. Where had those hours gone? Loath though I was to leave his arms, I forced myself to sit up.

"I should go," I said quietly. "I told him I would be back tonight." Sebastian didn't speak; he just watched as I shakily got out of bed and started to redress. I tried to put myself back in order as well as possible, but beneath my clothing, there were bruises on my hips and bite marks on my shoulder… Awkward silence for several seconds.

"I'll tell him soon," I promised. "I will."

"It makes no difference to me whether he knows or not," was my lover's so-sensitive reply. "You're the one who feels guilty. Regardless of whether our 'secret' gets out…I look forward to another night like this. Perhaps next time you'll be able to give me your full attention." Knowing that he wanted it sent shivers of delight up my spine.

"Maybe," I agreed, leaning in to kiss him until my breath was gone. "Mmh. Good night, Sebastian." That smirk of his stayed firmly fixed in my mind as I walked home.

When I arrived, I found William's bedroom light still on. It was past one in the morning; why would he still be awake? As I stepped inside, I found him sitting on the edge of the bed, staring at the ground. He looked awful: jacket and waistcoat gone, sleeves pushed up, hair messy… When he looked up, I saw that his eyes were red and bloodshot. Had he been…crying?

"What are you doing up?" I asked, brushing his hair aside. "It's so late."

"I was waiting for you," he said, seeming so glad to see me. "I said I would." He was so genuine and sweet, so enamored of me and considerate of my feelings… He didn't deserve what I was doing to him. Sitting down by his side, I took his hand and held it tightly, letting him lean his head on my shoulder.

"William…we need to talk," I said gently. "I'm not…quite sure how to say it…and I know it's going to hurt you, but I don't want to keep lying…" Silence. "Will?" I turned to glanced down at him…and he was asleep. For a moment, I thought of waking him, but I couldn't. Not for news like this. So I turned out the lights and lay down next to him.

Tomorrow, I told myself. Definitely tomorrow…