Well, that took longer than I thought. This chapter was harder to write than I thought it would be, so I hope you enjoy it. Oh, and this is where the M rating comes in, even though I did make an effort to be less graphic because I don't want this story to be removed.

A Union

"Thank you."

Jace looked at Clary, his eyebrow arching in question.

"What for?" Jace reached out, tugging on the hem of Clary's shirt to pull her to him, stopping when there was just an inch of space left between their bodies.

"For always protecting me, even when you can't physically be with me." Clary reached up to tuck a loose curl behind his ear, and then tentatively placed her hands on his chest.

"It's really my own selfishness that causes me to do that. You are what I value most in this world, so I'll do everything in my power to make sure you come back to me safely."

Clary rolled her eyes. "I'm attending a wedding, hardly what I would consider a dangerous activity. You, on the other hand, will be battling who knows how many Forsaken. It's you who needs to come back safely to me. Please be careful out there tomorrow. Don't do anything risky."

"Now where's the fun in that?" Jace smirked, looking down into Clary's eyes in time to see a flash of anger.

"There's nothing 'fun' about putting yourself in danger, Jace. It's not worth it. Please, promise me you'll be careful. Let the 'babysitters,' as you call them, do their job."

"I'll … try."

Clary cocked her head to the side and gave him 'the look.'

Jace held his hands up in mock surrender. "Fine. I'll be careful. I promise." He made a big display of making an 'X' over his heart.

Somewhere in the distance, Clary heard footsteps approaching. She grabbed a handful of Jace's shirt and yanked him through the doorway and into her room, closing the door quietly behind them.

"What was—" Clary placed a finger over his lips to silence him, then replaced her finger with her own lips. She was done talking, and done worrying for now. Now, all she wanted was to get lost in Jace—in his scent, in the taste of his lips, and the feel of his body pressed against hers. Holy fire be damned. She didn't care if he burned her. To touch him without holding back would be worth it. Whatever mark left on her body from his touch would serve as a welcome reminder.

In his momentary surprise, Jace kissed her back, spurred on by Clary's sudden boldness. As soon as his hands wound in Clary's hair and cupped the back of her neck, his body went rigged. She sighed in frustration into his open mouth when it stilled above hers. He was pushing her away.

Clary gripped his shoulders, her fingernails digging into his skin. "Please, Jace. Don't stop. Just let me have this, just for tonight."

He was already shaking his head. "You know I can't, Clary. I couldn't bear to hurt you. Trust me, I want to. God knows I want to, but I can't. I'd never forgive myself if I hurt you."

She turned away from him in frustration, her mind whirling. I'm the fragile one, she thought. I'm the one who needs protecting. Protection from my own boyfriend.

Tears stung at the back of her eyes, further proving her own inner monologue. She was the weak one. Clary bit her lip and squeezed her eyes shut, unwilling to let the tears fall. She took a few calming breaths and tried to slow her erratic pulse.

Electricity shot through her the moment Jace touched her arm and an image flashed behind her eyelids. A rune, comprised of three vertical lines, linked together by two half circles crossing through them. The rune spoke of strength and resilience; of fortitude, impenetrable. Still, this wasn't a rune intended for battle. No, in the back of her mind, something told her that this rune was meant for her, for now.

Bending, she quickly retrieved her stele from her boot and began applying the new rune to the inside of her upper arm. The three slashes came first.

"What is that?" Jace had come up behind her, peering over her shoulder.

"A rune I just saw in my head." Clary completed the rune with the two arching half-circles, linking the three slashes together. The rune glowed red, sending a jolt of energy through her.

"What does it do?" Jace reached out and touched the newly-made rune.

"I'm not exactly sure."

"You're skin feels … hard. Not like stone, but harder and colder than normal." Jace ran his hands up and down her arm with a look of mixed fear and fascination.

A huge grin came to Clary's face with the realization of what the rune's purpose was. "It's an antidote."

"An antidote? To what?"

"To your heavenly fire."

"Clary, you're sure that's what the rune is for?"

"I know it is, Jace. I know what I was thinking of when I saw the rune. Whenever one comes to mind, it's always the answer to whatever dilemma I'm faced with."

Jace just stared at her. "So, you're telling me that the Angels granted you a rune to be able to 'be intimate' with your boyfriend? It hardly seems like that would be serving the 'greater good.'"

"Why do you have to question the why, Jace?" Clary pulled both his hands into hers, guiding them to her waist as she rested her head on his chest. She could hear his heart beating faster than a hummingbird's wings. His hands rested feather-light own her skin, afraid to really touch her. "You won't hurt me," she spoke with one hundred percent certainty while looking up into his eyes.

"How can you be so sure?" His eyes were tight, reserved.

"This is my ability. This is what I do, and I have to have complete faith in it. Please, just trust me."

Jace stood frozen, an unreadable expression on his face for what felt to Clary like an hour. When a sigh escaped his lips, she looked away, crestfallen. The sudden absence of his hands on her waist was all the confirmation she needed. Rune or no rune, he wouldn't touch her.

So, imagine her utter surprise when Jace took her face between both his hands and kissed her the way he did back in Idris among the ruins of Wayland manor. Now, just as then, his hands gripped her with desperation, as if he knew at any moment she could be ripped from his grasp.

Clary clung just as desperately to him. Her hands twisted into his hair and raked over the smooth planes of his back, digging into the thin cotton of his shirt. She wanted the material gone—wanted to feel the heat of his bare flesh under her hands and against her skin—but was afraid to break their kiss. Afraid that doing so would break the spell, and he would go back to being the careful Jace who held her like spun glass in his hands.

"You'll tell me if I hurt you?" Jace whispered against her lips. Clary nodded in response. That was all the confirmation he needed.

His hands quickly smoothed down her back, molding her to him, until he reached the curve of her ass. Fingers dug into her leggings, lifting and guiding her until her legs were firmly wrapped around his waist. In two strides, he reached the bed.

Pulling away from her lips, he watched her as he lowered her to the bed—his golden eyes searching for any sign of hesitation or fear but finding none. His breath hitched at the sight of her. Scarlet curls splayed around Clary's head in fiery halo. Lips, swollen and pink from their kisses. Eyes, alight with a fire that coursed under a sea of green. She was more beautiful than he could bear.

Clary watched as his eyes roamed over her body. She felt naked beneath his gaze. Naked, but unashamed. Unable to stand the space between them any longer, she grasped the front of his shirt and pulled him to her.

Jace's mouth met hers, all teeth and lips, and tongue. He sucked her bottom lip between his teeth, nipping playfully. Clary groaned in response, arching her back to press against the length of his body.

She ran her hands up his back beneath his shirt, relishing in the way his muscles bunched and rippled beneath her touch. She wanted to touch more of him—all of him.

As if he could read her mind, Jace pulled away for the briefest of seconds to remove his shirt. Clary smiled against his lips, her hands fully roaming over his now-exposed back and up and down his sides. Emboldened, she slid her hand beneath the waistband of his jeans, her eyes watching him for a reaction.

He stilled above her, a shuddering breath escaped his lips. His eyes sprung open, gold turning into molten lava. Clary didn't move as she watched the flame lick its way under his flesh along the fine tracery of veins. She didn't fear the burn that never came. Instead, she smiled a smug smile.

"I didn't burn you." It wasn't a question. Jace's face broke out into a broad smile. He buried his face in the crook of her neck, peppering it with light kisses. "Why couldn't you have come up with this rune, oh, I don't know, two months ago?" He chuckled as he spoke against her skin.

Clary slapped him lightly on the back, but couldn't help but laugh, too.

Jace groaned and snaked his arms beneath her body, running his hands along the bare skin of her back beneath her shirt.

"Jace. Stop." Clary pushed against him, and he immediately withdrew with a bewildered look of concern. Jace sat up, resting on his heels as Clary pulled herself into a sitting position.

Catching his eye with a devilish smirk, she pulled her shirt over her head, throwing it to the floor. "What? It's only fair."

Taking advantage of her speechless boyfriend, Clary scooted forward on her knees and grabbed his belt, pulling him forward. Now, both on their knees with no space between them, Jace finally recovered.

"Well, if we're really being fair, then you're bra," he snaked his left hand around her back while never taking his eyes off of hers, "needs to go." With deft fingers, he unhooked it, sliding it carefully down her arms. With the garment discarded, he pulled back to take in Clary's exposed flesh. He leaned down, brushing his lips against hers. "You are so beautiful." His hands ran up and down her body, memorizing every dip and curve of her exposed skin until stopping at the waistband of her leggings. He caught her eye, his eyebrow raised in question. Clary nodded, giving him permission.

Jace hooked his thumbs beneath the elastic and slowly pulled the material down. Clary complied, lifting her knees until she was kneeling before him in only her panties. Thank goodness she had worn a nice pair of lacy, black boy shorts.

Jace audibly gulped and rocked back on his heels, not-so-subtly-adjusting himself from the strain against his jeans.

The movement drew Clary's attention. She couldn't help but stare at his crotch, sudden panic flashing through her.

"Clary," Wide green eyes met tawny ones, "we don't have to do this right now." He reached out and pulled her to him, his hands smoothing down her wild red locks.

"No, I want to. It's just that I heard it … hurts."

Jace pulled away and drew Clary's chin up to look him in the eyes, his thumb running along her cheek. "Lie down. Just close your eyes and try to relax."

Clary did as he instructed.

Taking a deep breath and blowing it out, Clary willed her muscles to unwind and closed her eyes. She felt the tickle of his hair before feeling the warmth of his lips on hers, slow and hungry. Warm hands began to roam over her body and she felt herself relax further under his careful touches.

His lips worked their way down to her jaw, her neck, and the dip between her collar bones. His hands came up to cup her breasts, thumbs running lightly across her nipples. Clary's breathing hitched, her body going rigid and heat coiling in her belly. Jace's lips replaced his hand, sucking her nipple into his mouth. A jolt of electricity shot through Clary, causing her whole body to buckle and a low moan to escape her mouth.

As Jace sucked and nipped at her left breast, his right hand slid down the smooth skin of her stomach and over the delicate lace of her panties. Clary's eyes shot open with a gasp feeling the delicious friction. "Jace—oh God." Her back arched against his hand, craving more of his touch.

She nearly came undone when his hand slipped beneath the lace, his thumb making small circles over the most sensitive part of her body. She was so lost in sensation that she didn't notice when her panties disappeared and didn't care that the whole Institute could probably hear her moaning.

Clary did notice when the delicious friction between her legs suddenly stopped, replaced instead by something soft and wet and warm. Her eyes shot open in surprise and she tried to back away from Jace. Instead, he just gripped her thighs harder, holding her in place as he ran his tongue up her slit.

It felt so good, part of Clary—if she was being honest, a big part—never wanted him to stop. The other part of her was mortified. She wiggled and writhed beneath him—her body's response to the new sensations that were coursing through her. She fisted the sheets at her sides, though she really wanted to grip Jace's hair and pull him closer to her.

"Jace, please." She needed more, feeling something building in the pit of her stomach. Something coiling within her, wanting to break free.

She nearly screamed when he slipped a finger inside of her as he sucked and swirled his tongue over her clit. She began to move her hips to the rhythm he set as he pumped first one finger, then two, in and out of her. Finally unashamed, she laced her fingers through his curls, gripping him to her. Jace grunted in approval, adding a third finger. All the while, the sensation continued to build.

With Jace's free hand, he had managed to unbutton his jeans while still continuing his ministrations. With the taste of Clary on his lips, he broke free and climbed up the length of her body, his fingers still pumping in and out of her.

He had never seen her like this. His Clary, who had always seemed so fragile, so innocent, bucking beneath him like she was possessed. Her eyes glazed over with lust while pants and moans escaped her mouth. This Clary was wild, untamed, and seeing her like this nearly did him in.

Boldly, she was the one to grasp his hips as he hovered over her, pulling him closer. She whimpered when he removed his hand, suddenly feeling empty.

Jace braced himself on both arms above her. Wide, green eyes snapped to his as Clary gripped his shoulders. She knew what was coming next and was filled with both fear and anticipation.

Jace leaned down, kissing her tenderly as he centered himself over her. Clary's breathing hitched when she felt him at her entrance.

Slowly, Jace set a rhythm, each stroke burying him deeper inside her until he felt her barrier. He stilled inside of her, pulling away from her lips to stare into her eyes.

"It's okay, Jace." Clary swallowed her fear and tried to brace for the pain.

Jace buried his face in her neck, whispered "I love you" against her skin like a reverent prayer, and pushed the rest of his length inside of her.

Clary felt a burning pain as tears pricked at the corners of her eyes. She gripped tighter onto Jace's shoulders, fingernails pressing into his skin. Jace had gone completely still above her, giving her time to adjust. As the pain ebbed, she smoothed her hands down his back. He pulled away from the crook of her neck, his eyes pained.

Clary reached up to brush a loose curl away from his face, offering him a small smile. Then, tentatively, she rolled her hips beneath him, watching as a trembling breath slipped between his lips and his eyelids fluttered shut.

The uncomfortable ache was still there, but different somehow. The ache spurred Clary into motion, relishing the feeling as Jace slid in and out of her.

She loved the sensation of him inside of her, filling her, as much as she loved the idea of it. They were joined together in the most intimate of ways, and she had never felt more complete. Wanting to mold herself to him, she wrapped her legs around his hips, moaning when he slipped even deeper inside of her.

Clary marveled at how they fit together so perfectly—how they both moved in synchrony without a conscious thought. Nothing existed outside of the two of them. Outside of the here and now.

Without a word being passed between them, their pace quickened as Clary felt the heat coiling within her belly as electrical shocks pulsed out and down to her toes. She closed her eyes, lost in the sensation as it built within her.

Jace reached down and gripped her hip, pulling her impossibly closer to him, bending down to capture her lips. That's all that it took for Clary to tumble over the edge. She left every muscle in her body clench as wave after wave of pleasure washed over her.

Feeling her walls clamp around him triggered his own orgasm, riding it out as Clary quaked with the aftershocks of her own climax.

Their eyes locked for a long, silent moment, both trying to catch their breath. Clary's already flush face turned an even brighter shade of red as the corners of her mouth turned up in a timid smile, causing Jace to break out in a full toothy grin.

"Was it good for you?"

Clary's flush deepened. "Way to ruin a romantic moment," she chastised, but still found herself chuckling, sending strange sensations through their still-connected bodies.

His face took on a more serious expression. "No, I'm serious," he smoothed a hand over her cheek, "I was so afraid of hurting you, so afraid that you wouldn't really … enjoy it."

"Do you doubt your abilities, Casanova?"

"Clary, I've never been someone's first, and with you, … well the thought of possibly hurting you is what's stood in the way of us even trying for the last few months. And to think that pain for you would be unavoidable, heavenly fire or not—"

Clary reached up and touched his cheek, shushing him. "It was amazing. I couldn't have imagined anything more perfect."

So there you have it, the longest and most awkward (for me to write) lemon I've ever written.