Clarke glanced around the crime scene, taking in the blood splatter, the position of the bodies, trajectory of the bullets.

Everyone stood on the sidelines, like they always would when Clarke was in her 'psychic zone' (Jasper's words not hers. He liked to cal it her 'superpower', the ability to envision the recreation of the crime in her mind). Even Lexa had learnt not to interrupt her when she had this look on her face.

"Murder suicide," Clarke murmured, catching the detectives attention. Lexa readied her pen over her paper, waiting to jot down whatever Clarke said. "He-" Clarke pointed to the man on the ground, standing over him to position herself in the position he would've been in when committing the murders. She lifted her hand, her fingers in shape of a gun, pointing at the victims on the sofa in front of her. "One," Clarke lowered her thumb and jerked her hand up, signifying a gunshot, "two," she moved her fingers to the second victim before turning her finger-gun on herself, positioning the tips on her fingers against her lips. "Three."

Clarke turned and pointed down at the man bellow her, missing the back of his head.

"But why would someone kill his wife and sister?" Lexa frowned, tapping the tip of her pen against the note pad.

"What is his medical history?" Clarke asked as she pulled her gloves off with a loud slap.

"Doctors think he was suffered from early onset Alzheimer's." Lexa explained and that had Clarke frowning, this guy couldn't have been much older than twenty five.

"What does he do?" Clarke asked curiously. "What was his job?"

"He-" Lexa hummed, flicking through her notes to get to the part she was looking for. "Boxer."

Clarke hummed and nodded, turning to Jasper. "Have the ME check his brain for CTE."

"CTE?" Lexa frowned after Jasper had nodded.

"Chronic traumatic encephalopathy," Clarke offered, waving her hand against the left side of her head. "It's a disease that people get in professions such as American football and boxing- professions where concussions are common. It's a degenerative brain disease, a lot like Alzheimer's, if this guy had this disease then he isn't entirely to blame for what he did."

"Concussions are to blame for this?" Lexa waved her hand toward the scene on the sofa.

"The concussions cause lacerations on the brain, can even result in loss of tissue, it can completely alter a persons personality. Can transform the nicest person in the world to," Clarke motioned to the scene like Lexa had. "To this."

"That is-" Lexa frowned, trying to take in everything Clarke had just told her. "Really sad if it's true."

Clarke hummed in agreement, "The worst thing is that they know something is wrong, they know they aren't right, they aren't themselves, but the only way of diagnosing this condition of slicing into a persons brain."

"So they have to die?"

"Unless you are in the habit of slicing into live brains," Clarke quipped, dipping down to pick up her forensics bag and slinging it over her shoulder. "See you back at the precinct."

"How do you do it?" Lexa asked, barging into Clarke's lab.

"I see knocking was a one time thing," Clarke jibbed, closing the comic book she was currently reading, spinning in her chair to look at Lexa.

"I thought we were passed that," Lexa shrugged, moving to lean against Clarke's desk. "How do you do what you did today? What you do at every crime scene? I mean I've watched you for over two and a half months and I still can't figure it out."

"It's my job."

"It's also Jasper's job but he doesn't do what you do, it's like you can just close your eyes and picture what happened."

"Maybe it's my superpower." Clarke quipped, lifting the comic in her hand before throwing it onto her desk. "It's simple, really. I just look over the crime scene, compile all the fact then create a mental image of what had happened."

"Simple as that, eh?" Lexa smirked, picking up the comic on Clarke's desk. "The Flash," she hummed. "I didn't think you were a comic book fan."

"Those at Jasper's, we are going to watch the to series soon, I'm almost finished with those."

"So, what? It's a man who can run super fast?"

"He is the fastest man alive." Clarke explained, "he can run up to a mile under the speed of light."

"Not over?"

"Course not," Clarke sounded outraged at the suggestion. "Nothing is allowed to go faster than the speed of light, it's a rule in physics, Albert Einstein came up with it."

"You said nothing is allowed, does that mean he can? And who's going to stop him?"

"He can, seven times the speed of light actually, but the living tribunal, that's an entity who maintains order in the universe, warned him never to do it again." Clarke pipetted a small amount of the buffer into the final test tube before turning to look at Lexa. "In the real world, theoretically, if you can go faster then the speed of light , everything slows down."

"What do you mean?" Lexa asked, folding her arms as she leant back against Clarke's desk.

"Well, let's say you have a train going the speed of light, to the people on the train an hour might pass but to the people off the train a week could have passed."

"So, you go faster than the speed of light you travel forward in time?" Lexa reasoned.

"Theoretically. We could also use black holes to travel forward in time. Time slows around a black hole so if we can get close enough to feel its effects but keep far enough away that we don't get sucked in we should be able to travel forward in time."

"What about going back in time?" Lexa asked, picking up another one of the flash comics and reading over the cover. "Is that possible?"

"They have suggested using wormholes to travel back in time but that's much more complicated."

"How so?" Lexa arched her eyebrow inquisitively, looking at Clarke over the top of the comic.

"Well, say I invent a time machine, I travel back in time and kill my grandfather. That means I would never have been born, therefore couldn't have created the machine, which means I couldn't have traveled back in time to kill my grandfather. But that also means that, with my grandfather alive I would have been born and created the time machine to go back and kill him." Clarke explained. "You see the problem?"

"A paradox."

"The grandfather paradox," Clarke nodded, "And you have the butterfly effect and the bootstrap paradox. Not to mention you could only go as far back as the time the wormhole was created which, boring."

"You are a forensic scientist, how do you know so much about quantum mechanics?"

"It's a hobby,"

"Quantum mechanics is a hobby?" Lexa snorted, flicked the comic book in her hand opened. "Okay."

Clarke watched Lexa as she read over the first couple of pages, her eyes watching how Lexa gnawed on her bottom lip as she concentrated. It wasn't until she noticed the lips moving that she realised Lexa was looking at her.

"Hm?" Clarke questioned, averting her eyes from Lexa to the test tubes.

"He's a forensic scientist."

"Oh, yeah. Jasper said it makes him relatable. Which would also make Dexter Morgan relatable."

"Who?"

"You've never seen Dexter?" Clarke frowned, looking offended at the notion Lexa had never seen the show. "What have you been doing with your life?"

"Catching murderers." And, fair point, catching murderers would take up a lot of a person time.

"You should watch it, if you have time."

"I'll have a look," Lexa agreed, throwing the book back onto her desk. "Anyway, I have to get back to work."

"No problem, detective." Clarke gave Lexa a two finger salute, causing the detective to grin at the ridiculousness of it. Clarke wanted to punch herself.

"You're a bit of a dork, aren't you?"

"You say that like its a bad thing," Clarke grinned cheekily at Lexa.

"Definitely not," Lexa shook her head. "I can't remember the last time I heard someone talk so- fervidly about something before, it was nice."

"How can you not be excited about it, you know?"

"Maybe I just don't understand it well enough." Lexa shrugged, pulling the door to Clarke's lab open. "Maybe you can explain it to me sometime? Show me a few documentaries, even."

"Oh, uh- yeah. Yeah, sure, whenever you want."

"Okay, I've got a bad guys to catch, but I will talk to you later."

Clarke nodded, waiting for the door to close behind Lexa before walking over to sit at her desk.

"I just saw Lexa leave," Jasper announced, quickly sliding into her lab. "Did you guys make out?"

"No, Jasper."

"Shame," the boy huffed, sounding genuinely disappointed as he left the lab.

Clarke tilted her head curiously as she stared at board in front of her, her lips wrapped around around the straw of her slushie and her legs swinging. This guy, the Manhattan Maniac as the force had so fondly taken to calling him (and they have a cheek to call her a dork, with their love of giving serial killers names), had evaded capture for well over two years now.

It wasn't Clarke's case, it was Cage's (unfortunately) but Clarke was curious. There was always something about serial killers, psychopaths, and sociopaths that peeked her her attention. God knows what that says about her.

"Well, don't you look jovial." A voice commented, startling Clarke out of her little daze. Clarke's head snapped to the door, a little smile appearing around her straw. "You are out of your lab."

"What- I..." Clarke gasped in mock shock, glancing around the room. "You're right, this isn't my lab."

Lexa grinned at Clarke's joke, moving to lean against the table Clarke was sitting on, folding her arms across her chest.

"What're you doing, doctor Griffin?" Lexa asked, her eyes traveling to the board.

"I've finished all my work, figured I'd come in here and update myself on this case."

"This isn't your case,"

"True, but I'm curious." Clarke shrugged. "This guy- I don't know- they call him a maniac but he's not." Clarke squinted at the board wth one eye and rubbed her ear. "Like, yeah, he's crazy but he's not a maniac. He is meticulous, clean. He drains his victims of their blood by slicing the artery in the neck, like they do with cattle, then he cuts their body parts into equal portions. Usually, I could get a read on him but there is nothing. He doesn't distinguish between men and women, there's not specific age, race. He just kills, and I don't know about you, but that scares me more than someone who has a specific profile."

"You just hate the fact this is the first person you can figure out."

"Yeah, that's part of it. But this guy is dangerous, he has already wracked up ten bodies over the past two years. We need him off the streets but it's like he is always one step ahead of us."

"When was the last time you slept?" Lexa asked with a little laugh, lifting her wrist, causing the black Apple Watch she was sporting to brighten. "It's almost midnight, you definitely shouldn't be drinking one of those this late."

"That's the good thing about being an adult," Clarke shook the drink she had almost finished, licking her lips with her blue stained tongue. "You get to drink ice cold cups of sugar at an hour of the day."

"Then you are clearly adulting very well," Lexa grinned playfully, averting her eyes back to the board. "You're right about this guy though, there's something about him, about this case, that we are missing. And whatever it is is fundamental to solving this case."

"Mm, I agree." Clarke hummed, glancing over at Lexa. "Why are you still here?"

"Same reason you are," Lexa shrugged. "I was looking over the evidence for this case."

"Are you planning on staying much longer?"

"Why? Am I cutting into your quiet time?"

"No, I was actually going to suggest I go get us some food and we can try and figure this out?"

"Don't you have someone to go home too?"

"Officer Blake," Clarke shrugged, shaking her head when Lexa's eyebrows raised questioningly. "No, it's not like that. She's my best friend. Beside it's my day off tomorrow so I can sleep in."

"Ok, you're on."

Clarke nodded, sliding off the table and dropping her cup into the trash can. "I will head out to get food, you can get all the evidence ready. Want anything in particular?"

"How about pizza? I've been here over three months and I've yet to see any proof that the pizza in New York is the best."

"There is a great place on west one-forty-fifth." Clarke patted her jacket to ensure she had her keys and phone. "Traffic shouldn't be to bad at this time, I'll be back in a half hour."

Clarke headed too Kings Pizza, ordering a large pepperoni pizza, stuffed crust of course, then headed to the local 7/11.

Lexa was sitting at the table Clarke had previously been sitting on, two boxes of what Clarke assumed was evidence sitting on the surface. Lexa looked up as she entered, eyeing the two large slushies, bag of candy and pizza box in Clarke's hands.

"How have your teeth not rotted to nothing?" Lexa laughed quietly, holding out a fist full of money.

Clarke waved her off, sitting down beside Lexa. "Ok, is this all the evidence we have?"

"Pretty much," Lexa hummed.

Clarke opened one of the boxes and peered inside. "There has been ten victims, how is this all you guys have?"

"It's all that we have found, this guy is ridiculously clean." Lexa frowned, watching Clarke as she opened the pizza box and tore off the lid, setting it in front of Lexa before motioning toward the pizza.

"People always leave a trail, there's no way he couldn't have left any kind of evidence."

"I know, but Cage hasn't found anything."

Clarke scoffed. "Let's be real, Cage couldn't find his own hand in front of his face. Let me reread his reports."

Lexa handed Clarke the files, extremely thin files Clarke noted, and Clarke opened one, absentmindedly chewing on the tip of a slice of pizza.

"I've been over everything multiple times and there is nothing here. He's like a ghost,"

"No one is a ghost, detective, not in this day and age. There's a way of finding this guy." Clarke huffed and Lexa watched as she took a drink of her new slushie, red this time. "Have you cross referenced the names? See if they have anything in common?"

"Nothing, hell, one of them had just moved from Canada two weeks prior. The only thing they have in common was that they worked in laboratories. Not in the same lab, or even the same field, just labs."

"Well, that has to be something."

"Nothing has come to fruition,"

"He has been killing at a steady rate, ten in twenty two months, one ever two months." Clarke said, lifting her eyes to look at Lexa. "He's due."

"Is that why you were in here? You knew there would be another killing soon."

"I suppose," Clarke shrugged, pointing down at the files on the victims. "These people, they don't have anyone in the city. Their relations are either dead, estranged or half way across the world. This guy knows no one will be looking for them."

"Then why not do what every other serial killer does and go after street walker or the homeless."

Clarke shoulders lifted in a shrugged, a sheepish little grimace appearing in her face when she dropped a small amount tomato sauce onto the page. "Sorry,"

Lexa smiled fondly, rolling her eyes. "It's fine,"

They stayed at the precinct, going over everything they had until Clarke was rubbing her eyes, aching from the extensive length of time she had been wearing her contacts, and she noticed lightening of the sky outside.

"We should probably head home," Clarke said, her voice gruffly and sleepy.

Lexa blinked, glancing down at her watch. "No point, my shift starts in three hours." She yawned, stretching her arms over her head.

"Are you kidding? You didn't say you were working today."

"Yeah," Lexa rubbed her eyes with her fists. "I think I'm just going to crash on the sofa in the break room."

"You're crazy, how the hell are you going to make it through the day?" Clarke frowned as she stood up, putting all of their trash into a bag.

"Coffee," Lexa said with a sad chuckle. "A lot of coffee."

"Well, good luck with that." Clarke laughed, gently patting Lexa's shoulder as she walked passed. "See you tomorrow, probably."

"Thanks for this,"

"No problem."

Clarke dropped the trash in the bin as she left, being met be a worried looking Octavia as she entered the house. "There you are!"

"Yeah, I stayed a little later at work." Clarke explained with a yawn. "And now I'm going to sleep all day."

"Next time call, or at least leave your damn phone on." Octavia called after her as Clarke slumped into her room, falling face first onto her bed.