A/N: The muse has decided it really enjoys writing for Shadowhunters. (If any of my followers haven't seen that show yet, I highly recommend it!) I'm setting this after season 2 but before 3, and I haven't included anything from spoilers, plus I'm not going too deeply into Jace's post-resurrection issues. This is just a fun little "episode," or whatever the equivalent of a case!fic is in this fandom.

Disclaimer: Not mine. Thanks to 29Pieces for beta reading (since I got her hooked *g*).

Chapter 1

Alec moved through the streets of Brooklyn, having to weave around mundanes who couldn't see past his glamour to avoid bumping into him. With how everyone was absorbed in their cell phones these days, though, it was a wonder he even needed to bother with the invisibility. No one was observant enough to even mark the shadowhunter tattoos visible on his neck, nor probably his bow and quiver. But the glamour was standard procedure, even when he was just on his way home after a day of work at the Institute.

Funny how he'd started thinking of Magnus's loft as home, rather than where he'd grown up. But Alec had gradually started spending more nights there, and he just felt…comfortable. At home.

Except, Magnus currently wasn't there. Usually when he was out of town on business, Alec would just stay at the Institute, but people kept vying for a minute—or several—with him to discuss the various changes he'd been implementing as the new Head, and he just needed a break from it all. So he'd decided to call it a night and come home to the loft, even though the person who made it home wasn't there waiting for him.

Someone else was, however. Luke was standing outside Magnus's door, one hand leaning against it as though he'd been knocking. The Alpha straightened at Alec's arrival.

"Alec," he greeted.

"Luke. You looking for Magnus?"

"Yeah." Luke glanced back at the closed doors. "I was surprised to find the place locked."

"Magnus is in Hong Kong on warlock business."

Luke let out a sigh. "That explains why he didn't answer my call. When is he due back?"

"Not for a few days," Alec replied, pausing as he noted the tension in Luke's micro expressions. "Is there something I can help you with?"

Luke shook his head in apparent frustration. "A wolf from my pack turned up dead under mysterious circumstances. There were no wounds on the body, and it was rapidly aged, almost mummified. Has to be magic, maybe a demon."

Alec's mouth turned down at the information. He'd never heard of anything like that before. "If you're willing to transfer the body to the Institute, we can do an examination."

Luke pursed his lips. "I'm not sure how my pack will feel about that, but I'll make the arrangements."

Alec nodded. "Where was the body found?"

"Opposite side of the docks from the Jade Wolf. Close enough to home but far enough away no one would have heard or seen anything."

"I'll check the shadowhunter sensor logs for demonic activity in the area."

Luke gave him a small nod. "Thanks. I appreciate it."

"Of course," Alec responded. They were allies, after all. The relationships he wanted to build with the Downworld wasn't for show.

They walked down to the street together and then parted ways, Alec heading back to the Institute. So much for getting away from work for a bit.

Isabelle's heels clacked loudly through the Institute's corridors, passing the training room, then the kitchen. If her brothers couldn't be found in either of those places in the morning, then there was one other common place to check.

Sure enough, when she opened the door to Alec's office, she found him asleep on the couch. Isabelle walked over and nudged him gently. Alec jolted awake, and Izzy suppressed a fond sigh; considering their major victory over Valentine, her brother should not be so tense. But he always did carry so many burdens, the weightiest being the expectations he put upon himself.

"I thought you went back to the loft last night," she said, taking note that he hadn't changed clothes from yesterday.

Alec swung his legs over the edge of the cushions and sat up, rubbing his face. "I did, but then I ran into Luke. One of his wolves was killed and he thinks it might have been a demon. I was going over the sensor logs."

He stood up and went over to his desk where a tablet was laying, screen black. Alec picked it up and started swiping through the contents.

"And did you find anything?"

He shook his head. "Sensors didn't pick up anything."

"Maybe it's not a demon," Isabelle suggested.

"Maybe," Alec murmured, then set the tablet down with a sigh. "Or maybe the sensors aren't functioning properly. We haven't been able to find all those demons that came through the rift."

Izzy frowned, but quickly dismissed that possibility. "No. We should have gotten alarms if the sensors failed."

"Still, I might send a team out to check them anyway."

Isabelle supposed that couldn't hurt, just to be safe.

Alec's phone pinged, and he pulled it out to look at the screen. "Luke's bringing the body here," he relayed, then looked up with that small smile of his. "You up for an autopsy?"

"Do you even have to ask?" she replied with a smirk of her own.

Alec's mouth quirked. "We'll meet you in the lab."

Izzy nodded and headed down to the lab to get everything in order. She put a lab coat on over her tight leather outfit and wrapped her ponytail into a firm bun. She had just finished laying all her instruments out on a cart when Alec came in with Luke, followed by an attendant pushing a gurney laden with a body bag.

Isabelle walked over and reached to undo the zipper. She pulled back in shock at the condition of the body. Her dear brother hadn't mentioned this. The body was partially curled into a fetal position, completely desiccated skin stretched tautly over shriveled muscles. The face was unrecognizable, and the mouth was petrified open in what might have been a scream.

"By the Angel," she breathed.

"Exactly," Luke spoke up. "I've never seen anything like this before."

"How were you able to identify it was a wolf?" Alec asked.

Luke pointed to the victim's neck. "That chain, plus the clothes were what Kevin was last seen wearing. And his scent is all over the clothes. The body…that's harder to tell. Obviously, it wouldn't smell normal."

Izzy hummed as she leant in closer, using gloved hands to carefully pick at the hems of the clothes. "I don't see any ichor. If it is a demon, it might be a greater one. Something cunning enough not to leave a mess." She frowned. "I don't see any wounds."

"We didn't see any, either," Luke confirmed.

Isabelle straightened. "I'll have to run more tests, do a more thorough examination."

Luke slowly nodded. "I'd appreciate it if you wouldn't take too long, and that you'd take care with the body. My pack wants to give Kevin a proper burial."

Izzy nodded quickly in return. "Of course. I will be respectful."

Luke inclined his head in appreciation.

"I'll look through the research we have here," Alec put in. "See if there's any mention of a demon that does this kind of thing."

"Thanks," Luke said, and turned to leave.

Alec walked him out, and Isabelle focused her full attention to the mystery before her. It was a good thing she was one of the top forensic pathologists in the city, because this looked like it was going to be a challenge.

Alec sat at the conference table, stacks of tomes both ancient and more modern taking up the bulk of the table space. Clary and Jace sat across from him with their own piles of research to comb through. They'd been at it all day, but unfortunately had not made much progress. Not because there just wasn't anything on demonic mummification, but because they kept distracting each other—Clary was constantly glancing at Jace, Alec could feel Jace's tension through their parabatai bond, and Jace was just plain distracted. He'd skim one page before fidgeting, or his gaze would go distant for a few minutes before he'd snap his attention back to the task at hand.

Alec wished he knew what to do for his brother. He knew Jace and Clary were hiding something about what happened at Lake Lyn. Alec had felt Jace die, and to find that he hadn't…obviously, Alec had never been more relieved. But there was still something under the surface and festering. Whatever had happened out there, it had been traumatic, for both of them. And they would open up when they were ready. Until then, Alec just had to weather Jace's volatility.

Speaking of which…Jace suddenly slammed the book he was reading closed.

"This is ridiculous. We're not gonna find anything."

"There's still a lot to go through," Clary pointed out patiently.

"Our time would be better spent out patrolling," he argued.

"Without knowing what we're up against, we can't be prepared," Alec countered.

Jace held up his hands in a gesture of, "Seraph blade. Demon's heart. I'm prepared."

He pushed away from the table abruptly. "I'm going out to patrol."

"Jace…" Clary started, but he was already marching away.

Alec's heart followed after his brother, and it killed him that Jace was keeping Alec out of whatever was bothering him. But what could he do? Jace would find him when he was ready.

"You should go too," he suggested to Clary.

She cast an apologetic look at the stacks of books, but hurried after Jace.

Alec suppressed a sigh as he roved his gaze over the research, but he nevertheless went back to it. Until his phone chimed and he pulled it out to find a message from Magnus: "Miss you," with a kissy-heart face emoji.

Alec couldn't help but smile, and he immediately typed out a response. "Miss you too. How's the meeting going?"

"Some warlocks can be such drama queens."

There was a split second before another message popped up.

"Yours truly excluded, of course."

"Of course," Alec replied with a smirk his boyfriend obviously couldn't see.

"How are things there?"

Alec grimaced, hoping the news wouldn't distress Magnus too much.

"I'm investigating what looks like a demon killing of a werewolf—mummification."

There was a longer beat before Magnus's next text came through. "That's…interesting."

Alec's thumbs flew over the screen. "Yeah. Working with Luke. I'll tell you about it when you get back."

"Alright. Take care."

Alec automatically typed out "Love you", and only paused briefly before hitting send. It was no different—or less meaningful—than saying it out loud. Magnus's response was instantaneous.

"Love you too."

Smiling to himself, Alec let the screen go dark on its own before he put his phone away and went back to his research.

Sometime later, Izzy's telltale heels clacked across the floor.

"Where did your research cohort go?"

Alec leaned back in his chair. "Jace was getting antsy and went to patrol. Clary went with him."

Izzy slid into a chair across from him. "I finished the autopsy. Didn't find much. There was significant bone loss, which one would expect to find from the natural aging process."

Alec quirked a brow. "Are you saying this wolf underwent rapid aging?"

"I have no idea. But there were no traces of demonic residue anywhere on the body. I'm sorry, I got nothing to go on."

"It's okay," Alec said, and pushed a book toward her. "We still have plenty of these to go through."

Isabelle scrunched her nose up at the volume of texts, but settled in to help. It was gonna be another long night.