AN: This story was sparked by a completely irrational love for Gabriel/Tessa, a ship that's yet to touch water. My thanks go out to Justine for the motivation and to F Elizabeth for the beta work.

"The Bible was written to show us how to go to heaven, not how the heavens go." - Cardinal Baronius, cited by Galileo.

How the Heavens Go: An Unlikely Story

Before the Drought

It was the same every night. Music, faint and yearning, pulling her from her sleep. The croon of a bow drawn along taught strings. A sound that grabbed at something deep in her belly and drew her to her feet. She should dance, she thought. Music that lovely should not be wasted. But she did not know any dances this mournful, this haunted. Her feet, at a loss of what to do, just carried her forward. Just like every night.

Jem with his back to her, white shirt hanging loosely from his shoulders like a ghost trembling in the brisk breeze from the open window and ever push and pull of his arm as it enticed poignant notes from the violin. Two candles were lit on the writing desk, neither of them enough to actually brighten the room. Instead their flickering light caught Jem's pale hair and the inky black runes just visible through his thin shirt. He was aware of her, she knew, even if he didn't turn around.

"Come here, Tessa."

She could hardly distinguish his soft prompting from the music. It was just as smooth, just as beautiful. And of course she did as he asked. It felt good to be close to Jem, as if she could reach out and take his hand without him minding. Tessa blushed even as the thought crossed her mind.

As soon as she reached Jem's side, he stopped playing, and Tessa nearly ached at the loss. The silence that followed was hallowing, but then Jem was lying aside the instrument and taking her in his arms, and she really didn't feel much but the heat of his body after that. He turned her, back against his strong chest.

It was always the same, and yet she never expected his hand to splay across her stomach and his chin to rest on her shoulder, his cheek is damp where it had rested again the wood only a moment ago. His fingers glided over her middle with all the grace of musician coaxing a ballad from his instrument of choice. Her eyes slipped closed so that there was only the touch of his hand over her dress and press of lips near her ear.

"I'm going to die," he said softly.

She knew he was right. They would all die someday, but Jem seemed closer to the edge than anyone, as if the slightest unplanned movement could send him plummeting. Tessa didn't like to think of a world that didn't have Jem in it. "Not tonight," she answered.

"No. Not tonight."

His hand had stilled, and Tessa felt the need to see his eyes and the way they were looking at her in that moment. She turned in his arms, but instead of finding Jem's silver eyes, she found the stormy blue of Will's. Before she could even reconcile her surprise, he leaned in and kissed her as if her parted lips had been waiting for him to take such initiative. Tessa lost her wits as quickly as she had the first time they'd kissed in the attic, and she found herself surrendering to his insistent hands as they tugged her closer, the space between their bodies disappearing. She kisses him with all the longing she'd been trying so hard to ignore and all the hurt she hadn't been able to hide from.

Her back came in contact with a wall, Will's heat and scent closing in around her from sides. His mouth left hers to leave a path of quick, hungry kisses along her jaw. Tessa gasped for air while her fingers curled in the dark fabric at his shoulders.

"I have to admit that I didn't think you would take me up on my offer."

Tessa shivered when his teeth graze her earlobe. "What do you mean?"

Will kissed her fiercely again, muttering against her lips, "I mean that you didn't seem the whorish type. You weren't like all the other girls who spread their legs as soon as I ask."

It felt as if her heart had gone still in her chest. Her limbs turned cold and heavy. "W-what…"

His smiled at her, amused. "It's a little late to be playing coy, don't you think?"

His fingers reached out toward her and instead of touching her chemise, they grazed the bare skin of her shoulder. Stifling a gasp of surprise, Tessa looked down to find her clothes gone, her nakedness vulnerable to Will's piercing gaze. Tessa tried to cover herself, but her hands were shaking and Will was laughing, some terrible, harsh sound that made her eyes sting with tears until she couldn't see.

She always woke up with the same sharp laughter echoing in her ears.

[ - ] [ - ] [ - ]

Tessa slowly made her way along the dark corridors of the Institute. The stones that normally kept the hallways lit had been extinguished several hours ago after everyone had turned in for the night. She kept one hand on the stone wall to direct her as she moved lethargically forward, her mind and steps still heavy with sleep.

The path from her room to the library was one of the few routes in the Institute she could take without getting turned around along the way. If the all the twisting and turning corridors of the Institute were its veins, then the library was its beating the heart, the place that made Tessa feel the most alive and the place she always managed to end back up in no matter where else she went.

She pulled the heavy door open and was surprised to find the room already well-lit. For a moment Tessa thought that it might already be in use, but the room was empty save for the rows of unopened books silently shouting for her attention. Tessa reasoned that Sophie must have forgotten to extinguish the lights before turning in for the night. It was perfectly likely since Sophie had had to take on a good deal of extra duties until Charlotte and Henry could find permanent replacements for Thomas and Agatha. Tessa's heart still ached at the thought of the two people who had lost their lives the night Mortmain had attacked the Institute and the loss of her brother. But it was a grief she tried not to linger on; no one else in the Institute seemed to, either.

Tessa crossed the room to the book case on the east wall, withdrawing from her pocket the small brass key she'd guilt Charlotte into giving her. When she held it, Tessa felt as if entire worlds were in her hand—people and places that only existed between the covers of books. Worlds only she had access to. It made her heart beat a little faster in her chest as she stepped onto the first rung of the ladder and began her assent to the top shelf. There was a gap three books wide—three books that were sitting on the nightstand in her room—and Tessa reached for the next one to the right.

"Careful. You might fall."

The quiet words startled Tessa into whirling around, and the hem of her robe caught beneath her slipper, causing her to slip. There was a moment of breathless terror followed by an acute pain in her shin as it banged against the step below. Her right hand just managed to snag the side of the ladder and she steadied herself against it, heart in her throat.

Gabriel Lightwood was watching from a chair by the unlit fireplace. "Are you normally this clumsy, Ms. Gray?"

"What are you doing here?" she shot back and shakily started back down the ladder while shooting glances over her shoulder. "It's late."

Only once her feet were back on solid ground could Tessa breathe easily. Straightaway she padded over to where Gabriel was relaxing in a plush chair, still wearing his clothes from the day. A book was lying open across his lap, and Tessa was half-tempted to ask after the title.

"I'm here because the library is always empty this time of night." Gabriel shot her a pointed look. "Present circumstances excluded."

"Don't you sleep?" Gabriel was always one of the first people up and about in the morning—according to Jem. Tessa was more of late riser and tended to miss everyone at breakfast aside from Jessamine, who was always insisted plenty of rest was necessary for a healthy, fair complexion.

"A little." Gabriel shrugged, and Tessa thought this was the calmest she'd ever seen him. His green eyes, which were always so intense and piercing, seemed softer here in the dim witchlight of the library. As they dipped and moved down over her form they lacked the customary severity, taking her in the way someone would appraise a piece of art they were seeing for the first time. But Tessa had never been intimidated by Gabriel and his pride—which he often wielded like a sword. So when his eyes found her face again, she met his gaze evenly.

He stared back unflinchingly, tapped his fingers twice against the book in his lap, and then looked away. "You've come uncovered."

Tessa glanced down to find that, indeed, the tie of her robe had come undone—most likely as a result of her near-slip on the ladder—and the front was hanging open, exposing the nightgown underneath. It was indecently low in the front and made of a thin cotton that might as well have been transparent for all the modesty it lent. Cheeks warm, Tessa quickly pulled the robe closed and refastened it. Tessa looked anywhere but at Gabriel. "Well, I'm—"

"And what about you?

Tessa cleared her throat. "Pardon?"

"Do you sleep?" he clarified, and it didn't take more than a moment for Tessa to realize he was genuinely curious. For all their resources, the Shadowhunters and their Clave still weren't any closer to a satisfactory explanation for Tessa's gifts. All they could agree on was that she wasn't human.

Tessa had to swallow back her bitterness before replying. "Of course I sleep. I do everything you do."

"Except I don't borrow other people's faces and thoughts."

Tessa had nothing to say to that, and Gabriel contemplated her in silence a moment longer before flipping close the book in his lap. He stood with a sigh. "If you sleep, you must dream." He walked to the nearest shelf, where the protective grate was already gaping open, and slid the book into an empty slot. "Are they nightmares, then, that have you up at this hour? I imagine that living in such close quarters with Herondale is enough to inspire night terrors the likes of which are rarely seen."

Gabriel said 'Herondale' the way most people said 'ax murderer.' Tessa tried not to say his name at all. "Not too far off the mark, actually," she muttered quietly, but the surprised look on Gabriel's face said something for the regrettably impressive acoustics of the room.

He smirked crookedly—the closest thing to a genuine smile she'd ever seen him give. "And I thought you were so fond of him. What was it you said the first time we met? Something about me owing him an apology and not being worth his time?"

"Yes, well I meant it. You were being awful." She looked away then. "But I understand now that there may have been some basis for your accusations."

She felt the air move around her, and when she glanced back up, Gabriel was standing much closer than he had been a moment before. She had to lift her chin in order to look him in the eye. When he spoke, the words warmed her skin. "He hurt you, didn't he?"

"No," Tessa answered quickly, startled by the sudden furry of his gaze. "He didn't touch me. He just…"

…broke my heart before I had the chance to give it to him.

Feeling self-conscious, Tessa tucked a lock of hair behind her ear and more hesitantly added, "He only said some very untoward things which don't bear repeating."

She expected him to step away then, to make an unsympathetic comment about the frail nature of females. But he didn't. If anything, Tessa would have sworn he'd moved closer because she was quite unexpectedly staring at his mouth. She watched it part as he spoke softly. "There's a reason he has a reputation."

Tessa nodded almost absently. "Yes, I remember something about your sister—"

"Just don't let your guard down around him," he said quickly. "He's trouble. And several other words which don't bear repeating."

He added the last bit without a trace of irony, and Tessa felt her lips quirking into a grin even though she didn't feel like smiling. She couldn't see his eyes anymore; they were standing too close, and Gabriel was too tall (no boy was ever too tall). The top few buttons of his shirt were undone, revealing dark swirls of ink around the base of his neck. Tessa traced the dark runes with her eyes, following the sleek contours where they dipped beneath his collar bone and curled over a hint of toned chest before disappearing beneath starched, white fabric. There were faint scars, too—faded but just as elegant as the permanent Marks. They were exotic and strange but beautiful in some fundamental way.

Gabriel's voice came from somewhere near her ear. "If you don't have plans to sleep, how do you intend on passing the night?"

"In bed." Tessa felt Gabriel's sharp inhale, and she was glad he couldn't see her heated face as she hurried to add, "Reading that is. It soothes me. It will help me fall asleep eventually."

She told herself she should move then. She should step away, retrieve the book she came for, bid Gabriel goodnight, and make the most dignified exit she could yet manage. It was ridiculous for her to be here with him, alone, at night, barely dressed, and standing as close they were. If someone were to walk in on them like this, they'd assume the worst Wrongly assume the worst.

Tessa stayed exactly where she was.

"I have a more effective solution." He shifted then, his body brushing against hers as he reached a hand inside his unfastened jacket. Tessa found herself battling the temptation to press closer, to close that last inch between them. It became quite hard to breathe and think at the same time.

Something smooth was pressed into her hand, and Tessa looked down to find a slim glass vile filled with a milky, blue liquid.

"What is it?"

"A sleeping drought."

The glass was still warm with his body heat, and Tessa wondered how long he'd been carrying it around. She craned her neck to look at him, her nose nearly bumping his chin. "But aren't you going to use it?"

"This way we'll both make use of it." His eyes fell away from hers and slid almost subconsciously to her lips, where they lingered. "You take the drought, and I'll sleep better knowing you managed to get some rest as well."

Tessa felt something like a tightening in her chest, an aching awareness that sent goose bumps down her arms and prickled the back of her neck. Her heart beat faster, her lungs burned from lack of air, and all she could see was Gabriel's face hovering above her, still and unwavering. Unmoving.

If he would only move.

"Goodnight," he said quietly. "Tessa."

She stared back, waiting—hoping—for something she could only think of as more. She saw it there, barely contained in his soft eyes and parted mouth. But then Gabriel stepped away, leaving her with nothing but the vile in her hand and the cold that rushed to her in his absence.

As she struggled to force out a strangled 'goodnight,' Gabriel turned his back and walked to the nearest witchlight. He extinguished it with a single touch.

Tessa left the library, fingers held to her burning lips.

AN: This fic is a oneshot, but I have the story marked as incomplete because there's a chance I'll be updating it with more oneshots that occur in this little universe. If that happens, I'll probably change the summary but leave the title as it is. Feedback is appreciated, and if you're interested in reading more Gabriel/Tessa, let me know. :)