Disclaimer: I do not own the rights to the Mortal Instruments series or to the characters. All I own is my imagination, copies of the books, and the laptop I wrote this story on.

A/N: The last time I published any fanfiction was somewhere last year. It has been months and I really missed writing. My schedule has opened up just enough to allow me some much needed time for writing. I had this story written down on paper ever since I finished the series, but only got the chance to type and edit it this weekend. I very much liked the dark and forbidden appeal of Jace and Clary's relationship when they still believed that they were related, so for the purpose of this one-piece they do not know any better than that. The story takes place during City of Glass when Clary visits the Lightwoods in Alicante for the first time. I may have taken the liberty of editing some details to fit my idea. I hope I didn't disappoint.


"Even though it's hard loving you, all I can think about is where we will go beyond tonight..."

After Jace yelled at her, Clary left the room just as quickly as she had entered it. Her green eyes shone vibrantly with unleashed emotion, not wanting to get in a shouting match with Jace. She always felt like the loser in those. Where he was the cold and distant one-shutting off his more human emotions because that was what had to be done-she was the warm and accessible one. Clary wanted to follow her heart and most of the time, she did. Her reds and greens contrasted with his gloomier hues.

She ran upstairs without thinking, out of habit. It wasn't until she had already made it to the top of the staircase that she remembered this wasn't her home. Still, she didn't turn back. Her stubborn nature kept her from simply acknowledging her mistake and retreating back downstairs where she would be inclined to wait in a stranger's hallway. Instead she kept her feet moving down a different hallway, relieved to only come across Max. He was sprawled on the floor of the library. Books surrounded him, but he merely had eyes for the comic book directly in front of him.

Clary knocked and shot him a friendly smile. "Hi Max, remember me?"

His brow furrowed for a second before his mouth stretched into a welcoming smile. "Clary! What are you doing up here? Do I need to get out of this room too?"

She shook her head. "No. Actually, I got sent out of the room as well."

Max's eyebrows raised in interest. "What for?"

"For not calling before I dropped by," she formulated thoughtfully. "Jace didn't like that so much, so he yelled at me to leave."

"Yeah, he gets like that sometimes. It's stupid."

"Ditto." She took a step into the room. "Mind if I join you while I wait this out?"

Max nodded his head excitedly. "You can read with me."

"I'd like that," she said while walking over to him. "Is it okay for me to take off my shoes?" Clary asked while lowering herself to the floor.

"Are you wearing socks?"

"Uh huh."

"Then you're good."

She took off her boots and shrugged off her jacket, leaving her in black jeans and a black tank as she laid down onto her stomach next to Max.

About 30 minutes later, footsteps were heard coming up the stairs. Max looked up, but Clary didn't until he nudged her. Her green eyes raised to the golden ones boring down on her. There he stood in all of his attractive glory, leaning against the doorframe and looking down at her like she was a child that needed to be disciplined. Only he didn't see her as a child or even like his sister, no matter how wrong it should feel, sickening even. Jace only saw the allure in the red locks that complimented her eyes so well and hung freely across her shoulders and back.

The loose strands didn't obscure his view completely and he allowed his gaze to stray and brush over her bare arms and neck and even lower. He couldn't help it and it only fueled his anger. He should be strong enough to withstand this sick urge of his. She didn't even know how irresistible she could be, like a wholesome princess who didn't know she was the name the mirror deemed the most beautiful of all, but no one could envy or hate because of the place her heart was at. Jace had never despised inner beauty so much.

"Max, can you give me a moment with the rogue princess?"

It wasn't really a question and Max recognized this. He gave Clary an apologetic smile and gathered up his comic book. Clary sympathized with the younger boy and shook her head. "It's okay. How about I come find you after and we'll finish reading that?"

Jace snorted as he stood impatiently in the door's entrance. "If you're lucky she'll portal her way into your room."

Max's eyes lit up for a second. "Cool!"

Clary smiled as she watched Max leave the room, Jace briefly running his hand through the boy's hair as he passed him. Her smile faded and she pushed herself up and into a sitting position, not missing Jace's eyes as they dipped and rose with her cleavage. A brother should not be looking at his sister like that, but in a way it was punishment. She liked that she still got to him no matter what words he spewed at her.

"I'm guessing you weren't satisfied enough with the damage you've done?" She raked her fingers through her hair before crossing her arms, her eyes shooting daggers at him.

"Neither are you since you're still here." Jace didn't look at her as he said those words and kicked the door shut instead.

Clary involuntarily flinched, inwardly hating being in a fight with him. "Look, whatever you may think or however you may feel doesn't really matter to me at the moment. I came here for my mom and–"

"And you needed my family's help. My help."

Her eyes blazed at the condescension in his voice and she fired back. "Technically they're not your family, but I am and I wanted my family's help." Her words left shallow cuts like glass. There was a silence, but one that was building up to an explosion. Her next move was just as calculated as her last and she scrambled up from the floor, angry and frustrated. "And I was the one who saved your ass on that boat, or has pride fogged up that memory?"

"You need to stop," he told her.

"Just because I'm right." Clary scoffed. "All you do is tell me what I do wrong and make me feel bad."

"So you waited up here so you could pour your heart out to me?" Jace took a step closer to where she was now standing as he continued, "Or to put me in my place, or for an apology maybe." He chuckled.

She shook her head. "No."

"Then what for, Clary? What for? ...I already told you to leave."

During the argument Jace had moved closer to her, much closer. He was right there in her face. His proximity would normally entice her, but her touch was brief and harsh as she pushed him away from her. "Stop it. Stop it, Jace. Stop taking your anger out on me. God." Both of her hands disappeared into her hair frantically before she flung them aside. "I can't help that we are brother and sister, okay. I get that you hate it, but–"

"Hate it," Jace interrupted her rant, the words leaving a bad taste in his mouth. He shook his head at her. "You have no idea."

Clary threw him an incredulous look, opening her mouth to point out the obvious to him, but he raised his hand and flicked his fingers at her in a dismissive gesture. "We both know it's not the same for you."

"What's it, Jace?" she asked, seeking out his eyes with her own. She knew what he meant, but needed to hear him say it, admit to what was supposed to be so wrong but felt so right each time they were near one another. They were living out a Virginia Andrews storyline, only her life wasn't a plot twist and her feelings weren't validated enough so the reader would come to understand and simply accept that she was in love with her brother. Her very handsome brother with the hard lines to counter her softer ones.

Jace shook his head, unable to put it into words. Instead he told her what he had been telling her over and over ever since they had found out. "It's wrong. I'm not supposed to... feel like this."

Clary nodded. "Well, at least you've found someone to keep your mind off it," she flung the words at him as calmly as she could. "Maybe you'll fall in love with her..." she added with a shrug, trying to make her feelings appear more casual than they were.

"Love," he stated, after which his eyes sank deeply into hers. "Would it matter if I fell in love with someone else, or even did something as meaningless as sleep with her?"

Jace was purposely pushing at her and he watched her throat quiver as she swallowed. " Sex," Clary said the word, unable to do so without picturing herself on the couch behind them, with him on top of her, "is meaningless to... Jace," she breathed his name and he moved closer to her, drawn to her sensuality and vulnerability in that moment. The way she said his name was the most endearing thing he had ever heard. "It's your business, what you do with other girls. I mean, girls," she quickly corrected herself, knowing he was to blame for her fumbling.

"Right, because you don't look at me like that anymore." He pointed at her when he reached the two final words. His finger brushed her stomach, just barely, but she felt it.

Clary's hand slid downwards unbearably slow. She wetted her bottom lip and looked at him from beneath her lashes. "You mean like a boy who isn't my brother." She clasped his finger in between hers, intending to push his hand away and once again creating distance between them. But she didn't. "So I can actually feel jealous about walking in on you with some other girl and you having your hands on her, the way I can only think about when I'm lying in my bed in the dark with my door closed because of how wrong these feelings that I have for you are?"

She sounded frantic, as frantic as he had been, though her words had made his anger evaporate. Instead his heart now beat rapidly, not with adrenaline but with bottled-up want, and when Jace touched her, she felt the change. His fingertips left an electric trail as they slid under her tank and took hold of her side. He desperately needed skin on skin contact. "So you have something tangible to compare your thoughts to." It would've sounded cocky if it hadn't been for the breathless rasp in his voice.

His eyes melted into hers and for a second she didn't know where she ended and he began. But Clary could hear her own heart beat and remembered the blood that pumped it, the bad blood between them. She took a step backwards, wanting to separate from him, but he simply moved with her. "Jace, I don't want us to be this dark fantasy." She took another step back as he tried to move even closer, his fingers still on her.

"If you could only..." His eyes darted across her face as he searched for the words. "All this inside me, it needs a release. I can't hold it in, not when you're lying on the floor of the library, looking so–"

She gasped as her back hit against a bookcase. Her chest heaved and pressed alluringly against his. "Clary," he whispered her name, sending shivers down her spine, exciting her. "If you want me to stop, you need to say so right now."

It looked as if those words pained him when spoken and she couldn't take it anymore. "Jace," she said, pulling at his hand that she still was holding on to. Clary nearly moaned his name and she felt his fingers dig into her skin, taking a firm hold of her. With her free and she clutched at his shirt. "I need you to say my name the way you just did."

Clary's request threw Jace for a second, though a smug smile was in place quickly as he leaned in closer, his lips pressing lightly against her earlobe. "Clary," he breathed.

And that was when she pushed him, disentangling their bodies for a moment or two. She pushed him, placing her hands on his chest again to maneuver him backwards, guiding him with her body. Their lips were on each other even before Jace landed on the sofa. She straddled him, his fingers like hot wax as he grabbed her. His hold almost hurt as he held onto her and this moment, needing to keep his eyes open and on her to make sure it was real.

She had made the initial move, something that normally only happened in dreams that left him sweating and panting. Clary's eyes were closed, her lips guiding her as she dragged them from his down to his neck. The way her hips moved against his and how she hid her face in the hollow between his neck and shoulder made him grateful for the closed door. If anyone saw them like this, the way the friction made his body quiver and tremble...

He released a low moan, surprising her as he propelled himself forwards and her backwards until he had her on her back, squirming beneath him. The black lace of her bra was revealed to him and Jace ran his fingers experimentally along the frilly edges. Her eyes were on him, as were her hands as they slid underneath his shirt, touching those lines she always admired. Jace closed his eyes for a few seconds, his own fingers blindly reaching for the fabric of her tank. He pushed it upwards before lowering his head, his tongue touching her belly button. She said his name...

The same time another, more masculine voice did. "Jace... Clary? I was sent up here to make sure you two weren't killing each other."

Clary's questioning eyes flew over to Jace who had frozen and hadn't said a word yet. He was hoping the boy on the other side of the door would just go away. "Sebastian," he finally sighed. He threw Clary a longing look. She looked beautiful beneath him. "Clary..." he began.

She shook her head. "Just get off me, Jace."

He did as he was told and she scrambled into a sitting position. He gave her the few extra seconds she needed to compose herself, though he now knew that he'd always prefer her to look the way she did when he had her up against the bookcase, flushed and frenzied.

Jace opened the door and Sebastian stuck his head in. "As you can see we're both fine," Jace reassured the other boy, stepping aside so Sebastian could enter.

Sebastian's eyes found Clary. "I don't think we've officially met yet." He walked over to her to introduce himself, but her gaze lingered on Jace.

They would always only have eyes for each other, and staying away would be even harder now that they've had something to compare their thoughts to.

Reality was excruciatingly better.

Please review? I appreciate you taking the time to read this and would be grateful if you left behind a review? This is my first dabble into this pairing, so all comments and critiques are welcome. :)