This is just something me and my BFF came up with, I don't know what to do next but I like the idea that this fic is taking. If you have any ideas or tips, I would love to hear them.
I will most certainly continue, this is not a one shot but I don't know when I will update this story.

"I gave you my number. I thought you might call." Said the voice from behind the door and Hariel Lillian Potter 'Harry' wondered how in God's name she had landed in this situation. John stood before her with his coat open to reveal the bomb beneath it and Sherlock was thrumming with adrenalin besides her even though he tried to hide it. Two of Hariel's best friends, in danger and she could do virtually nothing about it. She had been in many situations like this when she was an Auror but she could not chance using her magic out of fear the criminal mastermind would use it to his advantage.

Harry still wondered how she ended up in another dangerous environment, it has been years since her Auror days where she hunted the leftover death eaters. It has also been years since she had noticed she didn't age anymore, this was due to the deathly hallows. The hallows had marked her as mistress of death therefor she could not age or die, she looked no older than 27 but in reality it had been ages. She didn't like to count the years, it reminded her of all the friends and family she had lost to time. The years had passed fast and she had lost them all. The only things left are the memories she has of times with them.

The magical community doesn't know she still lives, they all think a boy named Harry had saved them from Voldemort so many years ago. The higher-ups at the ministry still know but they leave her alone. Their laws don't have any effect on her and she can do as she pleases. This is because she is the most powerful witch alive; she can do wandless magic and commands two different wands. Her favorite is her holly wand but she also possesses the elder wand which is way more powerful than the other.

Harry had met John Watson at a support group meeting, the support group was for soldiers with PTSD. She and the doctor had many things in common and quickly became friends. They had gone in search of another flat mate to share an apartment and an old friend of John had pointed them towards Sherlock Holmes. The trio had quickly bonded on the thrill of adventure and the chase of criminals that Sherlock provided. Sherlock and John didn't know about her magic until the explosion happened not one day ago.

One day ago:
Harry had just succeeded in calming John and Sherlock down, they had an argument about John's blog and Sherlock not knowing about the earth revolving around the sun. It was quite stupid really but she didn't have much time to think about it. She had felt it just before it happened, the wards she had put around herself warned her something big and bad was about to happen. Her instincts took over and she flung her arms out and yelled "PROTEGO!". John and Sherlock turned around to look at her and saw something you could only believe if you witnessed it. A rounded sapphire shield formed in the space Harry her arms indicated and a split second later there was an explosion. The detective and blogger felt and saw it happen but they were somehow protected by the shield that Harry had made.

Harry lowered her arms afterwards and the shield disappeared. There was no damage to the apartment but the street outside was covered in ruble. The duo looked at the girl in astonishment and Harry laughed. "Well, this is awkward." She said

"What did you just do?" John asked.

"I may have saved our apartment from an explosion, some thanks might be appropriate." Harry sassed.

"You made a shield by uttering the Latin word 'protect'." Sherlock said it like a statement not an question.

"Yes, I did." Harry deadpanned.

"How?" John asked in astonishment while he looked at the raven haired woman before him.

"It is a lot of explaining to be honest so I'll give you the short version; I'm a witch." Harry said as she looked at her friends.

"You're a witch?" John said in an unbelieving tone.

"Yes, do you want me to repeat myself?" Harry said.

Sherlock looked into her bright, emerald eyes and saw no lies in them. "Explain please." The detective said.

"I have been a witch for my whole life, you are born with magic or you are not. When you are eleven you get a wand and go to a magical school for seven years to learn all about magic." Harry explained.

"You have a wand?" John asked with raised eyebrows.

"Even better, I have two." She answered him and produced both of them.

"You didn't use a wand a few minutes ago." Sherlock stated.

"I didn't, that is wandless magic. It's the most complicated form of magic and to my knowledge I am the only person in the wizarding community who can do that. You also have non-verbal magic, that is more common but still difficult." She explained while the men looked at her wands.

"Why do you have two wands?" John asked.

"Long story. This is my first wand, the one I got a long time ago when I was eleven." She said this while she held up her holly wand. "And this is the elder wand." She held the wand in question up for examination. "This is the most powerful wand that has ever been made. You can't lose a duel if you poses this wand." John and Sherlock looked at the wands and had the same thought. Why does she keep the old wand if she has the elder wand. Harry could sense the thought and explained. "The elder wand is just a precaution, I like my holly wand more." She left it at that, no need to explain the whole wandlore behind it all.

The men before her were silent and looked at her with anticipation. Harry smiled to herself and put the elder wand in a holster on her arm but didn't store her holly wand. She could sense the need for a demonstration so she pointed her wand in the air and said "Expecto Patronum." The effect was instant as a beautiful white stag flew out of her wand, galloped through the apartment and came to a halt besides the witch. Harry looked at it and gave a sad smile "Hello again Prongs." She said in a soft voice.

"What is that?" John asked.

"This is a Patronus, a unique guardian animal who will protect you against dementors. A dementor is a creature that will suck all the happiness out of you if it is in your vicinity but it can also give you a kiss and suck out your soul. You can only cast a Patronus with positive thoughts and emotions like thinking about a pleasant memory. This would really difficult with a dementor nearby." Harry explained and the Patronus disappeared afterwards.

"I have just one more question." John said after they had settled down into their respective armchairs and had gotten some tea to dispel the shock "I met you at a support group for soldiers with PTSD but why?"

Harry looked at him and when he looked into her eyes he saw her age true age in them, they were sad and full of pain. "The reason I was there is quite simple John. It is because when I was two years old, the darkest wizard of all time tried to kill me after he had just minutes before killed my parents. He failed and died in the process but not after he had given me the scar I now currently have on my forehead. From that time on I lived with my aunt and uncle who despised the wizarding world and treated me no better than a slave. When I was twelve, I killed a basilisk; a snake as large as this apartment building with the most poisonous venom on this world. When I was fourteen, I was abducted and my blood was used to resurrect the wizard who had tried to kill me when I was two so he could try to kill me again. At fifteen years old I watched my Godfather die in front of me and when I was seventeen I was on the run, a wanted criminal of a corrupted government. That same year I became the savior of the wizarding world but not before I was temporarily killed by the dark wizard who had originally tried to kill me. That is why I went to a support group for soldiers suffering from PTSD, because I am a soldier. Every time I close my eyes, I see the people who sacrificed themselves for me. I was the chosen one, I alone could defeat him because neither could life while the other survived."

"This happened just ten years ago?" John asked in astonishment and he looked into her eyes again only to see the incredible age he had seen just minutes before.

"No John." Harry said with a long and sad sigh. "This happened a century ago. In the process of defeating the wizard I obtained an old power that will never let me die as long as I wield it. I won't age until then." The words were spoken with a finality and John didn't inquire about it again.

Present day:
Harry looked on as the person behind the door walked into the room like he owned the place.
"Is that a British Army Browning L9A1 in your pocket? Or are you just pleased to see me?" He said as he walked nearer.

"Both." Sherlock answered and he pulled the gun in question out. Harry gave a start of surprise at the sight of the gun, she did not expect Sherlock to carry any sort of weapon on him.

"Jim Moriarty. Hi." The man said in a playful tone. "Jim? Jim from the hospital? Huh. Did I really make such a fleeting impression? But then I suppose that was rather the point." He continued in a flirting tone as he looked at the detective before him and Harry shifted uncomfortably at the words. "Oh hello." Moriarty said in a tone as if he hadn't noticed her before she moved. "This one wasn't present when we met." He was right, Harry had been absent when Jim from IT met John and Sherlock. Harry looked in the eyes of the criminal and saw the same thing she had seen in the eyes of Barty Crouch Jr. so long ago, the man was intelligent and didn't give a shit about the crimes he had committed, as long as it profited him in some way.

Moriarty on the other hand saw something he had never seen before; recognition, as if this woman had seen a man of his caliber before. "You're something different aren't you?" He said and Sherlock strategically placed himself somewhat before her. "Why did you bring your princess if you wanted to protect her, Sherlock?" The criminal asked with a teasing tone. Sherlock had opened his mouth to answer but Harry acted faster. She walked forward past Sherlock and John, Sherlock didn't expect her to do so and was to slow to act but John saw it coming. The doctor wanted to stop her but he feared he would blow them all up if he made a sudden move so he just pleaded with his eyes. It was all in vain though, Harry was looking in the eyes of Moriarty when she moved forwards and she didn't waver one bit, not until she stood in front of the criminal. "You're not scared." Moriarty stated. "Johnny boy over there is terrified of getting blown up and Sherlock is practically singing with nerves. But you… you aren't scared at all. You really are something else, princess." He finished.

Harry looked at the man before her, he was taller than she was so she had to look up slightly when she talked to him. "There is one thing I advise you to learn really fast if you want to survive an encounter with me." She said as her emerald eyes bored into him. "I am not, nor will I ever be a princess. Don't assume things about people, I have seen people more powerful than you meet their end through that medium. Most of them have met their end by my hand and I encourage you to learn from their mistakes." There was a slight pause in her speech and the criminal before her looked at her. He could see the truth of her words in her eyes. God, those eyes, they were full of memories and experience, they spoke of a past he could not comprehend. "I also advise to stay away from me and my friends. If something ever happens to them because of you." Harry's voice was low now, full of malice and contempt but also a promise and he could feel that this warning was no empty threat. "I. Will. Hunt. You. Down. And believe me when I say this; I will make you regret ever being born." She finished.

Moriarty looked at the woman before him, she couldn't be much older than 26 but he suspected she was 27. Her age was downplayed a bit by her unruly raven hair. She had a little bit of a fringe but it had moved somewhat due to her looking up at him and he could see the faint outline of a scar on her forehead.

"No one ever gets to me. And no one ever will." The criminal answered but Harry had seen that coming, the man before her was brilliant but just arrogant enough to dismiss her. He would however think twice of crossing her, he had seen her eyes, the eyes that were too old for her face and he had seen the truth.

Later when Moriarty had gone not once but twice, getting called away by who knows what. Harry mused to herself if she hadn't given away too much. Moriarty is a dangerously smart man but she just hoped that she could keep her friend safe without having to kill someone who had underestimated her. This is Voldemort all over again, isn't it? She thought to herself.