A/N: Hello loves! Wild story idea that came to me out of the blue, borne of my love for both Shadowhunters and Lucifer! Lemme know if you love it, hate it, should I continue it? XOXOX

Devil in the Details

Isabelle Lightwood woke up to sun streaming through a window, warming her from head to toe.

She rarely had time to indulge in such a feeling, luxuriating in the slow stretch of her body as she twisted out of the black silk sheets of the ridiculous California king bed in which she found herself lying. The rest of her surroundings were just as opulent: the stone walls and floors and glass wall of what had to be a penthouse apartment screaming wealth. Craning her head around the corner, she could see a bathroom just as big as the bedroom, and from down the step into a living space that could rival the size of the main hall in the Institute.

Whoever she had hooked up with last night must have been pretty important to live in a place like this.

It wasn't every day that Shadowhunters from New York were dispatched to Los Angeles. The Institute there was twice the size and could usually handle themselves. However, this was a difficult mission, the details of which not even Izzy bothered memorizing (all missions seemed to run together after a while, and she trusted her brother to make the right calls). Alec had sent a small group of just she, Jace, and Clary to go help their neighbors across the coast.

After the demons had been slayed and the mission completed, the three of them decided to have a little fun. Shadowhunters were not known for letting loose, and the inhabitants of the LA Institute were surprisingly uptight, even for Shadowhunter standards. So, when Izzy asked a couple local mundanes for the best place to have a good time, she toted her brother and his girlfriend across town to a club called Lux.

One look at Izzy's ensemble for the night and the bouncer let the three of them jump the line right into the thick of the action. Izzy remembered the throngs of people, the heavy beat of the music, the dance floor with the baby grand piano in the corner. Izzy remembered her first, second, and fourth shot of vodka. After that, everything got a little...fuzzy.

She might have had one too many drinks. She might have grinded on one too many strangers. She might have made out with Clary while Jace watched, dazed and horny. Jace and Clary might have ditched her soon after that to go have some fun of their own.

That's when memories of him came into play.

Him. Her hook up, the inhabitant of this ridiculously fancy apartment, the owner of the club down below. Tall, dark, and handsome with a magnetic smile and enough sex appeal to tempt a saint. She knew exactly what she was doing, beckoning him onto the dance floor and pulling him close, and he knew exactly what he was doing when he touched her in all the right places.

By the Angel, the sex was fantastic. His body was a sin, perfectly carved and sculpted underneath her fingers and tongue. She had glamoured her runes (mundanes tended to freak out when they saw them), but whenever he happened to touch them, electricity broke out across her skin, all her nerves buzzing and craving more. Izzy thought she had moves, but the things that he did, the tricks he knew that could get her from zero to a hundred instantly...there were no words adequate enough to describe. Izzy fell asleep exhausted but in the best way.

She usually wasn't the kind to spend the night, but after the night she'd had, Izzy needed the rest. Not only from the mind-blowing sex, but from the physical strain of slaying demons. A good night's sleep on the softest mattress she had ever lied on under the silkiest sheets she'd ever touched did just the trick.

Izzy didn't get his name, but that was alright. It wasn't like she was going to see him again, and he didn't seem the type to hang on to hook ups the morning after if his absence was anything to go by. They had both had their fun, and now it was over.

LA was amazing, but it was time to go home.

Getting up, Izzy made her way into the bathroom. The shower was just as luxurious as the bed, the water pressure perfect (not the harsh hail of rain that poured from the Institute's shower heads) and warm, the towels downy and soft. She moisturized her skin with some fancy cream she found on the counter, and brushed her teeth with one of the brushes she found under the sink. A part of Izzy was tempted to raid the closet; judging by the quality of suit she had pulled from her hook up's body the night before, he was bound to have some fancy threads. However, she picked her clothes from off the floor, following the trail into the living area where she recovered her heels and underwear.

Izzy was not shy. She had no problem dropping her towel right then and there and get dressed in front of the glass. She was high up enough that there was no one to spy on her anyway. Her clothes felt slightly grimy, her skirt a little too tight with dried sweat, but she had dealt with worse. She buckled her bra, threw over her bustier, and started a search for her phone.

It was sitting on the bar next to two half-finished glasses of whisky, the one that was hers still sporting a ring of red lipstick. A few cigarette butts sat in an ashtray that were definitely not there the night before. That confirmed her theory about her hook up's lack of commitment. He had clearly been up before Izzy but left a sleeping stranger alone in his apartment. So either he was crazy, or he was rich enough not to care if she robbed him blind. Judging on her surroundings, Izzy was inclined to think the latter.

Mundanes, Izzy scoffed as she pressed her home screen.

There were a couple texts from Alec asking about how the mission went, one from Clary from last night that made absolutely zero sense - followed up by an apology text from an hour ago, and two missed calls from Jace around the same time.

Izzy clicked on Jace's contact and the phone picked up on the first ring.

"Hey, where are you?" came Jace's concerned voice, though there was still that lingering hint of hangover.

"Safe. I never left the club last night. You?"

"At a hotel with Clary."

"Oooo, care to elaborate?" Izzy asked, wearing a shit eating grin that Jace could probably hear through the line.

"Only if you go first," Jace shot back, both of them familiar with this little game. It happened every time they went out together, as both of them were prone to bad decisions. Now, it was only Izzy making the bad decisions.

"We can swap stories after we get back and debrief with Alec."

"Deal," Jace agreed, and there was rustling on his end that was probably him and Clary clearing out of whatever hotel room they'd managed to snag. "Meet you outside the LA Institute in twenty."

"See you soon."

Izzy hung up, strapped on her heels, and surveyed the apartment one last time to make sure she didn't leave anything important behind. She had her whip wrapped around her wrist, her stele in her pocket, and the Lightwood pendant around her neck. All other things were replaceable. Tall, dark, and handsome could keep them as mementos.

She knew last night would not be one she would soon forget.

...

Downtown, Lucifer pulled his 1962 black corvette over and turned off the engine, the Detective wasting no time jumping from her seat and onto the pavement. Honestly, had she no respect for scuffing the leather?

Still, Lucifer locked the corvette behind him and trailed after her. There was once a time he would have flayed anyone who dared insinuate that he resembled a puppy nipping after his master's heels, but he had slowly grown to accept this part in his dynamic with the Detective. The truth was, he was glad to stand in her shadow, if only because he could bask in it. Everything about the Detective was infuriating and complicated and...wonderful. He did not understand it, but sure enough, his universe had shifted to revolve around Chloe Decker.

"So, what kind of activities do you have planned for us today?" Lucifer asked, curious as to what was on the agenda. "Hopefully a good murder."

"Stakeout," Chloe shot down his excitement at seeing a dead body, her gaze fixed down the alley. "There's been a lot of suspicious activity around this area lately. We need to get a layout of it first, check for any escape routes and other ways someone could sneak their way in and out of here."

"And what exactly, Detective, are you hoping to catch?"

"I don't know yet...but something is going on, and I'm going to figure out what."

Normally, that line wouldn't faze Lucifer. He would have been content to smile and recline himself to the background while admiring the Detective doing all the work. However, in his reclining, Lucifer made the mistake of looking up and truly taking in his surroundings.

"Oh my," Lucifer gasped under his breath. This situation had suddenly gone from boring snooze-fest to a living nightmare. "Detective, I really don't think this area is where you should be looking."

"And why is that?"

Well, the giant Gothic cathedral inhabited by the cantankerous progeny of my most annoying little brother, who are not exactly Devil-friendly, is not the best place for a mortal to go waving around accusations of murder, was not an acceptable answer.

Just as he was formulating a comeback, the words died on his lips. If it were possible, the nightmare got worse.

Because there she was, the girl from last night, the one he had fantastic sex with until they were both unable to formulate sentences. Quite honestly, the best sex he'd had in a very long time. Except now, she was covered in tattoos that Lucifer distinctly recognized as runes, those pesky gifts given from Raziel to his followers. From where he stood, Lucifer was shielded from her line of sight, which was the only good part of this situation. She congregated on the front steps with two of her fellow Nephilim before disappearing into the church.

His one night stand was a Shadowhunter.

Bloody hell.