Keep in mind, this is one of my many first attempts at writing and completing a crossover fanfiction, so no burns, please. Constructive criticisms only.

I don't own Princess Principal, Moriarty the Patriot, the Sherlock Holmes original stories, or any other adaptations of Sherlock Holmes. I don't own any of its characters, or the image I used as the cover above. The only thing I own is the idea behind this crossover fanfiction.

It was a very early Friday morning in the Queen's Mayfair Academy.

It was late February, close to two months after the events transpired in the cathedral, which was both an assassination attempt and a coup attempt, and a month after the Principal Team took their well-deserved break in Casablanca.

Ange le Carre had gotten up from her bed and was getting ready for her day, even as the sun barely rose. Her roommate and fellow spy of the Commonwealth, Dorothy MacBean, followed her shortly.

They bathed and got into their Academy uniforms, with Ange getting the first turn as the first bird to rise.

After their preparations for the day, the two spies didn't go straight to class. Instead, they went into the Natural History Clubroom, which served as the headquarters of the Principal Team. Or, as they like to call it, Team White Pigeon.

As per Dorothy's orders the night before, the five of them were to be ready in the clubroom by 06:30 to discuss their plans for the day. As seen from the three girls seated around the round table in the clubroom, they had followed her instructions to the letter.

"Everyone's here. Good." After seeing everyone seated, the two Commonwealth spies sat in their respective seats to address the others.

"As you all know, a guest lecturer will visit Queen's Mayfair Academy today." Dorothy briefed as she pulled out a black and white photograph from her pocket and placed it on the table for everyone to see.

"Right, William James Moriarty. A professor currently teaching Mathematics at Durham University." Charlotte recognized, gazing at the photograph of said man on the table.

A handsome young man in his mid-20s, who had medium-length hair with long side bangs and a prolonged side fringe.

"The professor is quite charming," Beatrice commented on his good looks. "I have never seen such a young professor before."

"He's a genius and a prodigy, Beatrice."

"How did you know all that, Dorothy?"

"Control had given us some information on the professor and his two brothers, Albert James Moriarty and Louis James Moriarty." Dorothy continued as she placed two more photographs on the table.

The youngest looked similar to the professor, but the eldest bore no similarities to his two brothers.

"Adopted?" Beatrice observed.

"Yes. Albert adopted William and Louis into the Moriarty family. The three brothers were the sole survivors of the Moriarty family after the revolution. The Moriarty estate was set ablaze that night, killing their parents." Dorothy explained.

"But that's not all." Ange interrupted. "After the revolution, the three brothers continued their studies in the Kingdom. The three brothers were King's Scholars in Eton."

"Three of them?!" Beatrice didn't even bother to hide her shock.

"Yes, Beatrice," Dorothy confirmed.

"Lieutenant Colonel Albert James Moriarty is an Earl and a distinguished soldier in the Kingdom's Army. He exposed an illegal opium smuggling operation on behalf of the Kingdom's War Office a year ago." Ange continued.

"The Moriarty family head's loyalty to the Kingdom, coupled with the three brothers' intelligence, leads us to believe that William James Moriarty is a potential spy under the Kingdom's command." As Ange explained to the rest of the group, Dorothy gave her a slight nod in agreement.

"Wait, a potential spy?" Beatrice raised her voice as she panicked. "His first lecture will be in the princess' class!"

"Don't worry too much, Beatrice," Charlotte assured her while massaging her hand before looking at Ange. "Ange, don't you think it's too fast to jump to conclusions?"

"Like I said, he's a prodigy, princess. Not unlike a certain someone I know." Dorothy quickly answered, glancing at Ange, acknowledging her as the prodigy she was talking about.

And she, of all people, knew that Ange was one of the most dangerous individuals she had ever known. Cold and calculating. Deadly and licensed to kill.

"How do you know?" Charlotte asked.

"His intelligence makes him a potential asset to the Kingdom and a potential threat to the Commonwealth." Ange continued. "We'll treat him as such especially as he came to the Academy at the Kingdom's behest. It is most likely a foul play on the spymaster's behalf."

"Control ordered us to collect information, Ange, and not act until confirmation." Dorothy reminded her. "Until we have evidence proving your theories, they're just... shots in the dark."

"So, what do we do now?" The characteristically quiet Chise finally opened her mouth.

"We will continue our classes for the day. That means the two of you." Dorothy quickly pointed at the pair of roommates, Beatrice and Chise. "Ange and I will watch the princess during Professor Moriarty's lecture in her class."

"Alright, then. We better prepare for our classes." Charlotte said while giving a single clap of her hands, with no change to her cheerful demeanor. "Beatrice, would you be so kind as to prepare some tea for Ange and Dorothy?"

"Yes, princess." Beatrice acknowledged her beloved Princess' orders with a smile.

"That's very nice of you, princess." Dorothy complimented her generosity with a smile, surprised at the gesture.

"Well, both of you will watch me for my safety. This is the least I can do." Charlotte smiled, there was no lies behind her genuine kindness.

But still, she had something to ask.

"Ange? What will you do to him if you know he's a spy?"

It was a question Ange couldn't answer. It was still inconclusive at the time.

"I don't know, but I..."

"We'll determine that later. Right now, we are to collect information." Dorothy interrupted, beckoning Ange to come with her to the observation point.

Soon, the two spies of the Commonwealth set things up at their usual stakeout position at the foot of the tower on the rooftop.

The spot gave them a perfect view overlooking Charlotte's classroom. The angle they picked gave them a view of the class chalkboard and the front desk, as well as the door to the classroom.

As a precaution to prevent unexpected encounters with unwanted visitors, they locked the door to the tower.

A teapot and two teacups were placed on one of the staircases, right next to Dorothy, who was lying comfortably on one of them.

"Beatrice made some good tea." Dorothy took a sip of the tea Beatrice prepared for them both, sitting on the staircase.

"She has made tea for the princess dozens of times," Ange replied, not taking her eyes off the classroom window through the binoculars she was holding. "The princess regards her tea as the best in the world, no matter where they come from."

"Do you happen to know this type of tea, Ange?"

"Nuwara Eliya. From Sri Lanka."

"How do you know, Ange?"

"She told me personally."

"Don't lie to me, Ange." Dorothy accused jokingly. "I know you somehow memorized the taste and smell of every tea you come across."

"Maybe I do. Maybe I don't."

Dorothy laughed to herself as she knew she shouldn't expect anything else from Ange of all people.

But she knew one thing about the young woman in front of her. She was the smartest person she had ever known.

And there was another thing she knew about the two of them. Ange and the princess.

"Well, I know for a fact that the two of you are close. Is there something I need to know about?" Dorothy asked with a tone of curiosity.

"I'm just staying true to the mission, Dorothy." She put the binoculars down to face Dorothy. "Operation Changeling won't work without..."

Her justification was interrupted by the time on the clock.

"It's time," Dorothy told Ange as she looked at the pocket watch. "The class is starting, Ange."

Ange immediately kept an eye on the window through her binoculars. Dorothy followed suit.

On cue, Ange and Dorothy saw the classroom door opening, revealing the princess' homeroom teacher, followed by a young man wearing a brown, three-piece suit with a red tie, with looks matching the description in the photograph. He is quite tall, being six feet and one inch in height.

William James Moriarty.

Dorothy could see that he was more attractive in person, but those were merely trivial details to Ange, compared to the single feature that caught her eye most of all.

His scarlet eyes.

The spy felt those blood-red eyes of his piercing through every single student in the class. Including Charlotte.

"Good morning, everyone. This is Professor William James Moriarty. He'll be teaching mathematics for today." The homeroom welcomed the professor.

Ange may not be able to hear their words through such a distance, but she could read their lips perfectly.

He's calm and polite. That, she can see, from his smile to his students. A small, but warm smile. That smile didn't disappear from his face as he introduced himself to the class.

After introducing himself to the class as a whole, he began his lecture. The topic itself is familiar but trivial to Ange. Ange instantly recognized the equations the Professor wrote on the chalkboard and his announcement to the class.

"The Binomial Theorem."

"He got the professor's chair after he wrote a treatise on Binomial Theorem," Dorothy said. Ange merely acknowledged it with silence, knowing that fact already. "I've read it, Ange. It was... something."

The lecture went on for two hours. Amidst all that, Ange saw that he had complete control of the class and his equations.

For two hours, the entire class was in his control. Or, at least, the ones who understood his lecture or were interested in it.

From his teaching, Ange knew that Professor James Moriarty didn't merely grasp the theorem he was teaching. He had complete control of it. The written equations, the modified variables, and his control of both led to the subsequent results he had expected.

Just like a certain someone in the Kingdom.

Another thing she noticed about him was that he taught the entire class without using a single book on hand. She didn't remember seeing him bringing any into class. It's as if he had memorized everything beforehand and made good use of his memory, coupled with his extensive comprehension of the subject.

Just like herself, with such skills, he will make a good, no... brilliant spy.

During the last 30 minutes of the lecture, the professor suddenly gave the students a test. Five questions, all written from memory on the chalkboard. Each one was harder than the last, but they should have been easy if they had just paid attention to his lecture.

To the surprise of her classmates, Charlotte was the first to hand in her answers to the professor. But not to Ange, she knew Charlotte was brilliant.

Beneath the cold facade of the spy named Ange le Carre, a cheerful girl with long blonde hair smiled at the pickpocket, proud at what she had become in her eyes.

A true princess.

After everyone in the class had submitted the answers written on their papers, the professor ended the session.

"That went quite well. There is nothing off about him," Dorothy remarked as she turned to look at Ange, who didn't even bother to look back. "And it looks like he got a few admirers in the class."

Through the binoculars, Ange didn't fail to notice the princess staying behind after all her classmates were gone, all to thank him personally for the lecture, beaming all the while.

He got a few admirers, indeed.

When he gave her a short bow in response to her compliment, Ange couldn't help but think there was even more to this man than meets the eye.

After the princess got out of the room, Ange could see that Professor Moriarty was alone in class. After cleaning the board, and erasing the five questions he had written on it, he walked towards the door.

But, after a few steps, he froze in his tracks, much to her suspicion.

He merely stood in front of the doorway, but out of nowhere, he turned his back to gaze at the view outside the classroom window.

To Ange's surprise, she could see those blood-red eyes of his staring right at her through her binoculars. It was just for a split second, but in that split second, she felt a gust of cold wind passing through her very being, cooling her blood, and shaking her bones.

Did he know she was there?

Was he who she thought he was?

Did he know he was being watched?

Her questions remained unanswered after he got out of the room a few seconds later.

Either way, she couldn't risk another stakeout in the school. She knew she had to be cautious around the man.

She knew she had to find another way to obtain information from the man.

After the class, during the lunch break, Charlotte went to the school garden to give her report to Team White Pigeon, as they sat around one of the umbrella-covered tables.

"He's amazing!" Charlotte cried out excitedly. "Oh, his explanations were so eloquent and exquisite! And the test at the end of the class was a stroke of genius on his part." She took a sip of the tea contained in the cup she was holding.

"Focus, princess," Dorothy said sternly. "We need information whether the professor's a spy."

"All he did was teach us, Dorothy. I didn't see anything suspicious of him." She replied directly after putting the empty teacup on the table.

"I saw a meticulous man with the need to be in control of everything. All while staying above all that. He's a man who wouldn't let anything be amiss. No mistakes. No miscalculations." Ange profiled him from her observations.

"You know all that by simply observing his teaching methods?" Surprised at her keen observation, Beatrice asked, pouring yet another cup of tea for the Princess.

"What are you saying, Ange?" Charlotte asked, not liking the possible conclusion to her observation.

"If he's a spy, he's a good one. Just like me." Ange said. "Did he say anything about where he will be?"

"Yes. He's staying at the Mayfair Hotel nearby. Room 503."

"A hotel? I thought he would return to the Moriarty estate in Durham?" Dorothy asked.

"I thought so too. It's nearby. He told the entire class where he would be."

He disclosed his location to everyone in the class. "Why?"

"It will be our final opportunity to meet him and collect our work after he has finished checking them. He planned to return to Durham right after attending my piano concert in the grand opening of the Islington Hall tomorrow night." Charlotte explained.

Ange continued her questions. "How did you know that he'll be coming to your concert?"

"He told me at the end of the class."

"Good. I'll spy on the location. Tonight."

"Tonight?" Dorothy asked.

"It will be much more discreet. If he is a spy of the Kingdom, he must not have the slightest hint of our presence here." Ange replied, knowing she couldn't afford to be seen by him after the stakeout.

She then turned to team White Pigeon's resident ninja. "Chise, you're coming with me."

"Very well, Miss Ange. Our movements must be like the wind. Our presence a shadow in the night."

"Good. We'll leave at 8 p.m."

"Alright, Beatrice, Chise. The two of you will head straight to class. Report on whatever you find on the professor in his second lecture after you're done."

After giving Dorothy a nod of acknowledgment, the two of them immediately head to the lecture.

"They didn't find anything on him," Dorothy spoke to Ange as they sat on their respective beds in the room they shared. "Five questions, each one harder than the last. Just like the princess, but the questions were different." Ange thought. "The results were as expected. We will proceed with my plan." She immediately got up from her bed to change.

"Ange, are you sure you won't need me to drive you?" Dorothy asked as she looked away from Ange, and toward the window.

Before she knew it, the sun was setting fast, and a curtain of darkness fell on London.

"The roads in the vicinity of the hotel will be silent for the night. The engine of the car will attract unwanted attention. We don't want more of that." Ange answered with a bit of coldness in her voice as she put on her simpler spying outfit, which was just her student uniform worn over a black cloak, which functioned as a cape.

She had suggested Chise do the same in her preparations.

They did it that way for convenience, as they could easily assume the guise of unsuspecting students wanting to see the professor, an easy entry into the premises. Or they could play the part to improvise if the need arises.

"But it's going to rain soon, Ange." Dorothy turned around after noticing dark clouds quickly covering the streaks of orange in the sky, just to see Ange already put on most of her outfit, save for one piece.

"The rain never bothered me one bit. After all, no one will suspect any students wearing cloaks in the middle of the rain." Ange said as she put on her black top hat, finishing the look.

"Why would you be concerned now?" Ange walked towards the door.

Dorothy paid no mind to the harsh tone, being the warmer personality of the two.

"Well, you may catch a cold. I'm concerned about you being bedridden from a fever. That's what friends are for. We worry for each other."

Friends.

That single word made Ange stop in her tracks, right in front of the door.

Ange would never admit it in front of anyone, save for the one girl she held most dear in her heart, but she did enjoy the company of friends. And that meant the members of Team White Pigeon.

But still, they must never know who she truly was, or everything will be undone.

"Thank you, Dorothy," Ange whispered so silently that the wind itself couldn't hear her. "For being my friend."

Those were her silent last words to Dorothy before she opened the door and left under the cover of night with Chise.

The two spies took to the rooftops. Ange utilized her gravity-defying gadget, the C-Ball, to levitate from rooftop to rooftop.

Chise was able to catch up with her on foot, free-running across the rooftops.

They were moving fast, even with the rain. The constant rate of rainfalls muffled the noise their feet made on the drenched stones and tiles.

Chise was safe from the rain as well. She knew the straw hat she would usually wear in her spy outfit wouldn't match the cloak she was wearing. But she wasn't quite fond of the top hat Beatrice had offered her as a substitute.

Eventually, they reached the roof of the building next to the hotel, giving them the perfect position for a lookout.

Conveniently, they had a perfect view of the interiors of room 503 through a window on the east side of the hotel building.

Wordlessly, Ange observed the room with the binoculars she brought with her, while Chise stood to watch right next to her.

It was a simple room, well-lit by lamps. It had a single bed facing their left, with a painting hanging right above it. It had a desk table right next to the window, facing their right, and a smaller round table with a tea set placed on a tray on the far side of the bed.

Through the window, they could see the professor sitting on a chair in front of the desk next to the window. Ange knew he had done checking on the papers, as seen from the neatly placed stack of papers on the table by his side.

She could see Moriarty writing on a piece of paper with an envelope right next to it. There was no doubt in her mind as to what he was writing. A letter.

After writing on the piece of paper and putting it inside the envelope, she could see him turning his head to the door to his room.

He immediately dropped what he was doing and got to the door. Ange immediately knew that the professor had a guest knocking on the door.

It could be a liaison, a contact, or just a hotel staff, but she needed to see the face of the guest for confirmation.

Moriarty opened the door to reveal a dark-haired young man wearing a long-sleeved white dress shirt with blue rectangle cufflinks tucked into navy blue pants. Aside from that, he wore a black coat over his shirt and had a light blue scarf around his neck.

Ange estimated his age to be around Dorothy's age. Well, around Dorothy's real age.

"Oh, Fred, just in time." He greeted his guest with a smile as he entered his room.

"Hello, professor. How was the lecture in the academy?" He asked as he smiled warmly at the professor.

"It's fine. I need your help, Fred. Can you help me send this letter?" Moriarty took the letter from his desk and showed it to Fred.

"I'll put this in the post."

"No, Fred. The contents are quite confidential, for two pairs of eyes only, and I would prefer it if the letter reaches him as soon as possible. I don't want to keep him waiting."

Fred merely gave him an understanding smile. "In that case, I'll send it personally."

"The address is written on the envelope, Fred." He pointed out.

"Yes, professor."

"Thank you for this, Fred." Moriarty gave him a nod to show his gratitude.

As Fred left the room to send the letter, Ange evaluated what she saw.

Seeing the professor asking Fred for help so easily while treating Fred with respect and kindness, and Fred's obedience to the professor's request while reciprocating his respect, Ange knew then that Fred and the professor were close.

Less of a mere servant, and more of a ward.

As the two spies saw him getting out of the hotel, wearing his scarf as a hood, and going into a full sprint to the destination in the middle of the rain, they ran after him.

He ran quite a distance, away from the hotel, which was located in High-East London, and got even closer to Westminster.

As the two white pigeons in black flew after him in the rain, they didn't fail to notice that he was going even closer to the very heart of the Kingdom of Albion.

One look between the two birds was all it took for Ange to believe that her suspicions were correct.

The letter's contents were confidential to even his ward, and the professor wanted the letter to reach the male recipient as soon as possible, and he didn't want to keep him waiting.

Could it be...?

After following him for a while, he slowed down as he reached his destination. A flat, with the address written on it clear as day.

221B Baker Street.

A possible safe house?

As the door opened, Fred gave the letter to a young woman wearing a pink dress, with her long brown hair braided up at the back of her head.

She accepted the letter with a smile and let him leave.

As Fred left the premises, the young woman kept the door open and took the time to check on him, visibly worried about the young man running in the middle of the rain.

She closed the door as soon as he was out of her sight. That was all Ange needed to know she's a caring individual.

The two repositioned themselves around the corner, away from the spot overlooking the flat to discuss their findings and plan their next move.

"We found the recipient," Ange said.

"It's a peculiar place for a spy, Ange." Chise perched on the side of the rooftop.

"I need to get a closer look into the flat," Ange said as her eyes were quickly fixed on the building.

"Yes, but I don't think-"

Chise's words were interrupted by a sudden, intense pain blossoming in her shoulder as she plummeted from the rooftop and onto the wet ground.

As Ange went down to check on her, she tried to register what had happened. It was all very sudden, and before she knew it, Chise was right before her, on the ground, trying to ease the pain of her wound.

Ange held onto the gunshot wound on her left shoulder, keeping pressure on it. That's when she noticed that there was no exit wound and that her right knee was dislocated from the fall.

She was bleeding profusely from her shoulder. It can only mean that the bullet had hit an artery.

The plan was to get Chise to one of the nearby "hidden hospitals" prepared by the Commonwealth to heal the gunshot wound.

But a passer-by quickly beat her to it before she could even calculate a route.

In the rain, she heard gradual wet steps coming closer toward them. She quickly assumed her guise.

"Hey, what are you two doing here?" A man voiced out, before running towards them as he realized something was wrong. "What happened?"

Ange could see his features perfectly. From his ash-blonde hair with a greenish hue, his three-piece suit with a brown vest, and his concerned face.

After doing her observations in her spy persona, she quickly returned to her guise as a Queen's Mayfair Academy student.

"I... the two of us... we were walking, and all of a sudden, a man... pointed a gun at her and shot." Ange gave out heavy breaths as she fabricated what happened on the fly. A part of her guise, and a testament to her skills of deception.

"Who?" He looked around, searching for the nonexistent passer-by.

"I don't know. I didn't see his face. Please... help her." She expressed her emotions, shedding tears to sell the deception.

"Alright, let's bring her to my place. I live nearby. Right there." He pointed towards a building around the corner.

221B Baker Street.

Before she could understand his actions, and what it would mean for the two of them, he had already lifted Chise off the wet pavement. Ange instantly went to help him, staying close to him.

"Can you help her?"

"I'm a doctor." He said with determination in his voice. "I will help her. I promise."