Alright. I have been writing a Criminal Minds story and reading Castle ones. I searched for crossovers but didn't find any, so I decided to make one of my own. So here it is.

*Disclaimer: Do I own Criminal Minds or Castle? Hmm... let's go with a yes (in my dreams).

Interfectorum Mulierum

Kate Beckett sighed as she reached the crime scene. Esposito said this case was a weird one, but nothing could prepare her for what she was about to see. After parking her car, she stepped out into the chilly New York morning air. Surely Castle would be here soon and throw crazy theories.

She walked to the body and gasped. "What the hell?"

Esposito looked to her. "Weird, right? I've never seen anything like it."

"Castle's going to love this," Ryan said, staring at the woman's body.

"Oh, yes he will," Kate said as she bent down to examine the woman's body. Everything was unusual. The woman looked like she stepped out of a high budget Greek movie. Her blonde hair hung braided wrapped around her head with laurels embedded in it, gold weaving in the braid. She wore a blinding white chiton with gold trim. Brown leather sandals were tied loosely to her feet. She even wore jewelry that looked authentic. Golden armbands, necklaces, bracelets. Kate thought she looked like how an ancient Greek queen would have looked, thousands of years ago, well, without the giant stab wound in her heart. "Any ID?"

"Nope. Our little Grecian Queen here doesn't have anything on her, so we can't identify her."

Lanie said, "I'll get an ID if her finger prints are in the system."

"Ok, guys, what did I miss?" asked a breathless Castle. "Whoa."

"Preliminary TOD is about midnight to three in the morning. Also… these wounds weren't caused by a knife. It was by a blade longer than three feet. Our vic was killed by a sword," Lanie said, standing up.

"Wait 'til Gates hears about this one," Castle said, staring down at the woman.

Back at the precinct... "I am calling the FBI. We don't deal with these cases, detective," Gates ordered.

"Sir, please. What if someone is just trying to fake a serial killing to throw us off? The feds are busy people, we don't want to waste their time," Beckett pleaded. "Plus, you've got to hate them as much as I do," she added.

"Fine. We get any more bodies, I'm calling the BAU in Quantico. They have the best reputation around. They could get this case solved in a few days," Gates said, the authority clear and loud in her voice and words.

"Thank you, sir," Beckett said as she left her office.

"Yo, Beckett," Esposito called from his desk.

"Yeah?" she asked as she walked over.

"Vic's name is Penelope Caesura, age 25, worked in the museum majoring in Greek and Roman mythologies," he finished.

"Penelope?" Castle mused. "That's the name of Odysseus's wife. Her name means 'weaver of cunning,' and it fits her. She stalled suitors trying to marry her by claiming to weave her lost husband's shroud. She did, but only by day. At night, she'd-"

"Castle, that's irrelevant," Beckett cut in. She didn't need a mythology lesson.

"Irrelevant? Beckett, we found her in classic Greek clothing! It can't be a coincidence," Castle said, his face lighting up.

"C'mon, Castle. You know this is just someone trying to throw us off. Someone wanted this girl dead."

Gates walked out of her office and to them, silencing their conversation. "There's already another body," she said, turning on the news. A woman of the same age as Penelope only with brown hair was dressed the same and stabbed through the heart with a sword.

"There's no way this is a coincidence anymore," Castle murmured.

Kate Beckett bit her lip and sighed, clearly unhappy the feds were going to get called. "Sir, let us investigate more."

"If this is a serial killer, he's already progressing fast. This is not in our hands, Beckett. I'm calling the BAU."

"Hey, is it the one with David Rossi?" Castle asked with a smile on his face.

Gates looked to him apprehensively. "I'm not sure. Find what you can on these two victims and have it ready for them when they get here."

Beckett sat at her desk and watched as Castle took the seat next to her. "So who's David Rossi?" she asked, checking her email to see if there was anything new.

"An old friend of mine. Haven't you read any of his books?"

"Nope."

"Why, detective Beckett, I'm flattered. You only paid attention to my books."

She rolled her eyes and looked past him, to the murder board. "We should get to the next crime scene."

"Do you think it's a time traveling killer?" he asked.

"That theory again?" Beckett asked while putting her jacket on.

"Of course. They are all wearing Greek clothes." The two started walking to the elevator.

"Ok, genius. How did the Greeks make a time machine?" Beckett asked with a blinding white smile. "They didn't quite have that technology. We don't even have that technology. Also, the victims are in our system."

Castle paused for a second. "I said time traveling killer. I wonder if we'll meet Odysseus or-"

"Why would any of the Greek heroes come to the future and kill women and dress them in Greek chitons?"

"You know about Greek mythology, don't you?" he asked with a sly smile.

Beckett pursed her lips. "As I've said before, Castle. There's a lot you don't know about me." The elevator doors slid closed.

In Quantico, the BAU groaned at being called in. "Why can't I just have one personal day…" grumbled JJ as she mixed her coffee. Henry wasn't feeling well and he needed his mom, but nonetheless, there she was, in the office, ready to go to someplace and catch a criminal.

"JJ, bull pen, now," Hotch said as he passed by the break room. She sighed and followed him inside.

"Okay, so today there's been two murders that occurred at about the same time this morning in New York. The first victim was Penelope Caesura," Garcia said, awkwardly saying the name Penelope. Pictures of a woman in a Greek chiton and gold jewelry flashed on the screen. The white dress was stained with blood.

"What's with the Greek stuff?" Emily asked, staring at her tablet with a curious expression.

"The killer is most likely a psychopath, suffering from a delusion that he's a Greek hero of some sort," Reid mumbled, staring at the pictures.

"The second victim was Alexa Elias," Garcia said, showing pictures of a brunette with identical dress and jewelry. Even the stab wound in the same place. "Both women were found sexually assaulted and had this inscribed in their stomachs with a blade… interfectorum mulierum. I have no idea what that is or means."

"It's Latin," Reid said. "It means killer of women."

"You speak Latin?" Rossi asked him. "I should quit being surprised by now…"

"Even I knew that," Emily said, looking at the inscribed words.

"This is against the profile a bit," Morgan mentioned. "Latin is Roman. If this guy is dressing them as Greek, and he's obsessed with it, wouldn't he use Ancient Greek?"

"Maybe he counts them as one and the same. There were very little differences between the Greek and Roman empires. It's said that a Greek started Rome, anyway," Prentiss said.

Reid nodded. "Prentiss is right. Their mythology is nearly identical. The main difference was that Rome was more warlike and lasted longer. Other than that, it was the language."

"We'll finish briefing on the plane. It's up in twenty."

Everyone gathered their things and grabbed their go bag. They drove to their jet and took off to New York. Sitting there, they all were slightly amused by this case. Fairytale killings were heard of. How often did you come by a case with ancient Greece ways?

"Since there's only two victims, have they ruled out the idea of a personal connection between them and the killer?" Morgan asked.

"No. The captain of the 12th precinct requested us immediately. She warned us that the lead detective doesn't do well with FBI. She likes to be in charge. We want her to feel like we aren't stealing her case away."

"Her?" Prentiss asked.

"Her. Detective Kate Beckett," Hotch confirmed.

"Wait, did you say Kate Beckett?" Rossi asked.

"Do you know her?"

"No. But don't you all read?" Rossi asked around to his team.

Prentiss and Morgan nodded at the same time and said, "Kurt Vonnegut."

Reid said, "Mostly non fiction or sci-fi."

JJ blushed and said, "Teen fiction, mostly…"

Hotch just waited patiently for Rossi to continue.

"There's a writer named Richard Castle who works with a detective Kate Beckett to write books. He and I have been friends for a long time. He tags along with her and follows her cases," Rossi said nonchalantly.

"As a citizen?" JJ questioned.

"He's gone through paperwork, but he's not on the force."

"We can't have a civilian tagging along our investigation. He could leak things to the press we don't want out," Hotch said disapprovingly. "How could they allow that?" he wondered aloud.

"I don't think this detective will like it if we take him off the case," Morgan added uncomfortably. "This may not go down well."

"Hotch, I know Richard Castle. He can be a pain in the ass sometimes, but he's got a great mind. He could help us solve this," Rossi persuaded. "I'll offer to keep a close eye on him and make sure he doesn't leak things to the press."

"Fine. We don't want the lead detective on our bad side."

When the team of FBI agents arrived, Beckett's attitude dropped. She didn't want to meet them, but Gates ordered her to. "Hi, I'm detective Kate Beckett," she said when they took over her spot in the precinct.

"Agent Hotchner," the guy with black hair said. "I'm the unit chief."

"Nice to meet you."

"This is agents Morgan and JJ," he said, pointing to the buff guy and then the blonde girl.

"Hey," Beckett sighed. "Where's the rest of your team?" she asked for Gates' benefit. Castle had gone with Esposito and Ryan to Lanie to see the bodies. Normally, Beckett would have gone, but Gates ordered her to stay.

"Agents Prentiss and Reid went to see the crime scenes. Rossi went to the coroner's office."

Beckett wanted to correct him and say Lanie's, but she bit her tongue. Something about the feds annoyed her to no end. Almost always they were arrogant, self centered, just trying to make a name, and had she said arrogant?

"I already have my people covering the bodies."

"Well, Agent Rossi needs to look at the body so we can see what you don't," JJ answered instead of Hotch.

"What makes you so much better than us?" Beckett snapped.

"Um, sorry. We just look for different things than you do. You are trained to look at the big picture. We are trained to look at the minor details, things killers left behind to be noticed," JJ apologized, trying to remember this girl had a grudge against federal agents.

"My partner Castle does a great job of finding those things, JJ," Beckett said before sitting at her desk. "Anyway, I need to catch you all up. Current suspect is Jack Swanson, who-"

"He doesn't fit the profile," Morgan said.

"Excuse me?" Beckett asked to him.

"He means that the name Jack Swanson isn't Greek. Our unsub either was born with a Greek name or he changed it so it was Greek. Possibly Latin, given the words on the body," Hotch said.

"Well, I'm still going to run it down," she said, looking down at her paperwork. "A suspect is a suspect. He was last seen with Penelope and lives near where Alexa was dumped."

"All due respect, detective," JJ started, "but it won't turn out. Him living near the dumpsite of the second victim is just a coincidence."

Beckett sighed. She really hated these arrogant agents. "Fine. I'll call Ryan and let him know."

"Reid?" Prentiss asked, looking down at the dried blood on the alley floor. A tip of something bronze gleamed in the blood. "I found something."

He was behind her in seconds. Prentiss bent down and picked up the fragment with her gloved hands. "It looks like the tip of the sword," Reid mumbled. "We should get it cleaned up and inspect it."

"Yeah." She put the tip in a plastic bag and ducked under the crime scene tape with Reid in tow. "Now we need to see Penelope's crime scene."

Reid just nodded silently as they got into their vehicle and drove to the other alley. "This escalation is interesting and different. He's already escalated to killing two people at the same time without leaving trace evidence behind. He's matured enough to be calm and rational. We're dealing with someone who's killed before," Reid said, inspecting the sword tip in the plastic bag.

"What could have triggered his change of methods, though? The Greek aspect is unique enough to have been noticed earlier, even a decade back this would have been recognizable," Emily added in wonder as she parked where the next dumpsite was.

"Something big would have had to cause it. It could have been a child dying. If the unsub used to tell stories to a child about the Greek mythology, it could have triggered it. Also, he may have had a background knowledge of Latin previously."

Prentiss smiled and Reid's heart skipped a beat, like it always did when she smiled at him. "Come on, we should see this crime scene," she said before they got out.

There you have it. Chapter one. Anyway, let me know if it sucks and whether or not I should continue. If I do continue, then know that it'll touch base on all of them equally. In case you didn't notice, there might be a little Prentiss/Reid romance... or is there? Anyway, if you want it to continue, expect some surprises. Possibly Caskett at the end. We'll see.