Author's Note: I know Jace and Simon aren't everyone's favorite slash couple, but I've never been able to get that scene on Valentine's boat, Simon drinking Jace's blood, out of my head. And their relationship in City of Fallen Angels only becomes more complex. I hope, if you enjoy slash, that you enjoy this. The story takes place in the chapter "Wake the Dead" from City of Fallen Angels.

LOST SOULS

Leaning against the counter, Simon unscrewed the bottle of blood and took a swig. Normally he didn't like drinking the stuff in front of other people, but this was Jace, and he didn't care what Jace thought. Besides, it wasn't as if Jace hadn't seen him drink blood before. At least Kyle wasn't home. That would have been a hard one to explain to his new roommate. Nobody liked a guy who kept blood in the fridge.

Two Jaces eyed him – one the real Jace, the other his reflection in the windowpane. "You can't just skip feeding, you know."

Simon sighed. Even for a Shadowhunter, Jace could be annoyingly self-righteous. "Has it ever occurred to you that I don't like drinking blood?"

Jace blinked. His eyes were pale yellow tonight, like someone had sprinkled gold dust around his pupils. "You're a vampire. How can you not like drinking blood?"

"Maybe," said Simon, "I don't like being a vampire."

Jace flushed. Neck to hairline. Simon was shocked. Alec blushed all the time, but he had never seen Jace look the tiniest bit remorseful, for anything. He had never seen him look so…discomfited. "It was that or let you die," he said, harshly. "Which would you have preferred?"

Across Kyle's futon couch, they stared at one another, the angel boy and the vampire – Jace with his golden eyes and halo of curls, Simon with his poreless white skin and big, dark eyes. It was the first time either of them had ever referenced the night of Simon's Turning to the other. The night Jace had kissed Clary in the Seelie Court, and some essential piece of Simon's soul had broken, because it was so obvious they belonged to one another. Jace and Clary. Even the sound of their names together was like a heartbeat. Like a breath.

Though he didn't need to breathe any longer, Simon felt his chest rise and fall as Jace took a step toward him. There was something feline in the way he moved, as though ready to pounce, and Simon winced as his fangs slid down, piercing his lower lip. The bottle of blood, half-forgotten, slipped out of his hand, overturning in the sink. The smell made his stomach tighten.

"Well?" Jace said, padding closer. "You didn't answer me, vampire. Should I have let you die?"

I. Not we. Hadn't Clary been there, too, and Isabelle? "I don't blame you," Simon heard himself say, faintly. What the hell was happening to him? He could hear Jace's heart beating. Smell the sweat on his skin, the blood that flowed under it. Shadowhunters smell like sunlight, he had told Clary, when she had asked.

And Jace. Jace tasted of honey and roses and leather and starlight. Simon would rather have not known that, but he did know it, and he couldn't seem to forget it, much as he tried.

"I asked her, you know." Jace stopped, even with the counter, and looked at Simon. The collar of his T-shirt was pulled aside, revealing the small, silvery scar just above his collarbone. Simon squeezed his hands into fists behind his back. "I asked Clary if this was a life you would have wanted. If it had been me – "

"You would have let me kill you," Simon said, softly.

Jace went very still. The memory of that night on Valentine's boat – Jace's hands pressing Simon closer, Simon's arms forming a cage around him, hot, sweet blood flooding his mouth with every beat of the other boy's heart – stretched between them, a cord that could never be severed.

Simon never know who moved first, him or Jace. They both moved fast. Simon might have been just a tiny bit faster. He was definitely stronger. Not that it mattered, since Jace made no effort to fend him off as Simon slammed him up against the wall.

He was breathing roughly. The pulse hammering in his throat drew a moan from Simon; he shut his eyes, his hands clenched around Jace's shoulders. "What are you doing?" he groaned.

"What does it look like I'm doing?" Jace said, calmly.

It looked like he was trying to commit suicide. By tempting – oh, hell, Simon thought, he might as well just say it: by seducing a vampire. But he couldn't be that unhappy, could he? Whatever was going on with Clary, Jace couldn't really want to die. "I could kill you," he said, roughly, his voice muffled by his fangs, which were by now fully extended.

Breath fluttered close to Simon's ear. Jace had leaned toward him. "You won't," he whispered.

Simon moaned again. His head dipped, his actions almost outside of his control; there was thirst, yes, but not just thirst. Desire. He wanted to drink Jace's blood. He wanted to pierce that soft, fair skin with his fangs, feel that lean body go rigid against his at the initial stab of pain, then pliant, with pleasure. Wanted to taste the blood that had turned him into this thing he was. A Daylighter.

His lips skimmed Jace's collarbone. Jace caught his breath. "Simon – "

"Shh." One of Simon's hands slid up, tangling in those silky curls; he tilted Jace's head back just a little on his neck, breathing deep against his skin. Marks, black ribbons like spilled ink, unfurled underneath his T-shirt, scrolling across his chest, his arms, his back. "It's all right," Simon murmurred. "I won't hurt you…"

This, as his lips touched that small, silvery scar his fangs had made once before. Touched it, and as Jace gasped, tasted it, with a flick of his tongue; sweat burst like crystals of salt in his mouth, and Simon, unable to hold back any longer, bit down, tearing Jace's skin to free the blood beneath.

Jace cried out. He twisted; Simon clamped down hard with his fangs, flattening the taller boy against the wall with his smaller, slimmer body. Jace struggled, pushing against Simon's shoulders, but he didn't strike out at him, and Simon didn't know if that was because Jace was scared of the Mark on his forehead, or because he wanted someone to hurt him, or what. He was finding it hard to care, with Jace's blood filling up his mouth like nectar.

He didn't know how it was that he found the strength to pull away.

Jace stared at him, dazed, blood trickling down the front of his shirt. He was exceptionally pale, except for two spots of livid color on his cheekbones – and his lips, which were red and swollen, like he had been biting them. His hair was a tousled a mess. Simon's fingers were still wrapped up in it, their faces dangerously close.

When Jace's gaze dropped to his bloodstained lips, Simon had to swallow a whimper.

"Is that it?" Jace asked, huskily. "Is that all you want from me?"

Damn him to hell, it was like he knew, Simon thought, as heat rose in his face – as close as he could come to a blush. Simon didn't think of himself as gay. Then again, he didn't think of himself as a vampire, either. But ever since that night on Valentine's boat, he hadn't been able to get Jace Wayland (for he would always be Jace Wayland to Simon, the smirking, self-satisfied boy he had met on Luke's front porch, the day Clary had told him the Shadow World existed, and that she and Jace were part of it) out of his head. His scent. His taste. The pressure of his eyes when they sought you out across a crowded room. The half-smile he wore when he thought no one was looking, and his droll arrogance slipped into something far more intriguing.

With an effort, Simon mastered himself, standing up straight so he could look Jace in the eye. He didn't know his own milk-white skin was flushed, his coffee-black eyes bright as a bird's behind their thick lashes. "I'm not going to kill you," he said. "Sorry to let you down, but if that's what you're after, you'll just have to find another way."

"Kill me?" Jace recoiled like he'd been slapped. "You think I want you to…By the Angel, Simon, even if I wanted to die, you think I'd bring you into it? You think I'd want Clary or Isabelle or Alec to have to kill you?"

Simon stared at him. Jace looked so tired – shadows under his eyes, nerves strung around his mouth. And young. He looked desperately, hopelessly young, a little boy lost. Right now you think you do not need others of your kind. You are content with the friends you have – humans and Shadowhunters. But what about in ten years, when you are supposed to be twenty-six? In twenty years? Thirty? Do you think no one will notice that as they age and change, you do not?

"Simon?"

Jace's voice was soft. Simon blinked Camille away, blinked the flushed, disheveled boy he still had pressed up against the wall into focus. "No," he said, and his voice was almost angry. "That's not all I want from you."

Jace's light eyebrows raised. He was probably about to say something snide – he had gone ten minutes without a snarky comment, a record for him – but Simon ducked his head, brushing his mouth over Jace's, and stole the words right off his lips.

Jace's lips parted easily under just that soft pressure. If he minded that Simon tasted of blood, his blood, he didn't show it; he reached out to take Simon's waist, drawing him in for a long, deep kiss.

Simon swam into it, his arms sliding around Jace's shoulders, their bodies moving together as their mouths did, soft, hungry kisses that built a fire in Simon's core. He was hardly aware of shrugging his jacket off, of Jace pulling his shirt off over his head, his slim, scarred hands feathering across Simon's smooth, bare skin; he was aware only that kissing Jace was even more intoxicating than drinking from Jace, and there was some part of him that recognized, albeit dimly, that no vampire should have felt that way. But he wasn't kissing Jace as a vampire. He was kissing him as Simon Lewis, the way he would have kissed him when he was still just a regular mundane boy; and Jace was kissing him back, even though he was in love with Clary. Even though he was a Shadowhunter, and by rights, Simon's enemy.

What am I? Simon wondered, dizzily. What am I, to you?

He would have asked, but Jace was walking him backwards, into Simon's small bedroom. His shirt hit the floor on the threshold; Simon shoved him down on the pillows and crawled up the length of his body, toeing off his shoes as he kissed every thin, raised white white scar on Jace's stomach and chest, flicking his tongue out to the taste the blood dried on his throat. Jace shuddered under him. He was whispering, soft sounds of desire Simon wasn't sure he even knew he was making.

It sounded like, Don't stop.

Their mouths came together again, hotly this time. Simon's fangs sliced Jace's lower lip; instead of turning away, Jace pressed harder into the kiss, his hands fumbling at the buckle of Simon's jeans. Simon sucked gently on the tiny cut, prisms of color exploding behind his eyes as Jace's hands slipped inside his boxers.

"Simon," he said, thickly; for Simon, his vampire strength surprising even him, had flipped them over, so Jace was balanced on top of him. He felt like his body was splitting open, like he was coming apart at the seams; he could feel everything with Jace's blood coursing through his veins, sweeter, more potent than any drug. His skin was so achingly sensitive to the brush of Jace's lips, the whisper of his breath, that he was almost writhing as the other boy kissed down his neck, onto his chest.

His hand was still inside Simon's jeans, stroking, and it was all Simon could do not to scream, pleasure bordering on pain, thirst mingling with desire, hunger and want and need…and, oh God, he wanted to scream, even as the word turned to ashes in his mouth: Oh God, Jace, yes, please, yes –

A single, wordless cry escaped Simon. He fell back on the pillows, eyes wide, pupils dilated. Jace dipped his head, nibbling at his lips; Simon rolled him over, brushing silky strands of sweat-damp hair back from Jace's face. His beautiful, perfect face.

He didn't realize he was crying until Jace touched the tears on his cheeks. "What's wrong?" he whispered.

Simon shook his head. "I don't know," he whispered back, and he didn't. But he knew something was wrong, and not with him. With Jace.

Jace opened his arms. Simon laid his head down on his chest, listened to the frantic beats of his heart slowly return to normal. His heart. Simon circled his fingertips over the spot just above it, wondering who Jace's heart belonged to. Valentine? The Lightwoods? Clary? It wasn't to Simon, Simon knew that. What he didn't know was what desperate secret had driven Jace from Clary's arms into his tonight.

What was Jace trying to bleed out of himself now?

He lay there, wide awake, puzzling on that long after Jace had fallen asleep. It was a relief, really, to see him sleep, Simon thought. Sitting up, he kissed Jace's bruised-looking eyelids. The other boy smiled, murmurred softly. Not a name. A plea. Stay.

So Simon stayed – on the windowsill, arms wrapped around his knees, while all around them, as the moon climbed to its nightly perch, the city of New York thrummed out its undying pulse: vampires and werewolves and faeries and mundanes and Shadowhunters, and things, like Simon, like the boy asleep on his bed, that were somewhere in-between – a city of fallen angels; a city of lost souls.