Just so you all know, I've changed a few bits of information from both series so that it fit in with my idea. (For example, the power behind Magical Cores/Circuits, peoples personalities, some people are dead earlier than they should be, and how the Clock Tower and Dead Apostles are represented. Oh, and Potter!Bashing among others.)

Disclaimer: I do not own Harry Potter or Fate/Stay Night.

Prologue – Zelretch and the Einzberns

From the night Voldemort attacked the Potter twins, she had been called a squib.

Lily and James doted on her little brother. Charlus Sirius Potter was born a mere three minutes after her, and that was enough for Albus bloody Dumbledore to name him the 'Chosen One'.

She was ignored, for the most part. Even her godfather, Sirius, who had once loved her oh so dearly, hadn't glanced at her since the attack. Instead, he spent most of his time with Charlus, playing with him and helping James teach the little brat how to fly.

By the time she turned five, she had already taught herself how to read and write. She new that if she didn't teach herself, that she'd never learn.

After all, they hadn't acknowledged her in years.

So when the old man with red eyes suddenly appeared in her bedroom in Potter Manor on the Christmas morning during her fifth year, and wished her a Merry Christmas, she was quite shocked. She hadn't been spoken to in just under four years, after all.

"Merry Christmas, Helena Lillian Potter," he greeted cheerfully. Helena raised a brow. "I'm curious to know just how you managed to get passed the Potter wards without alerting my Father."

The man chuckled. "An old, old secret, my Dear, one I hope to pass on to you."

Helena cocked her head. "I'm afraid whatever magic you used I cannot perform. You see, I am a squib," she told him carefully.

The man smiled knowingly. "No, my dear; you are simply not a witch," he emphasized.

Helena took a seat at her desk, as the man was currently seated on her bed. "I'm afraid, sir, that I do not understand. If I am not a witch, then I am obviously a squib. There is simply nothing else I could be."

He nodded. "Normally, you would be right. However, not many witches and wizards are fond, or even aware of Mages."

The word mages made Helena confused. "I thought Mage was simply another word for wizard?" she asked the man.

He laughed. "No, dear child, a Mage is a person with Magical Circuits instead of a magical core. There is no limit to how powerful a Mage can be; however, very few wizards are powerful, as magical cores use up a lot more energy than circuits do."

Helena hummed. "I suppose it is possible, however I don't understand why you would believe me to be a mage." she replied, shaking her head.

"I am what's known as a Dead Apostle. Wizards call us vampires. As such, I have the ability to see not only a wizards core, but how many Circuits a mage has."

"How many circuits is normal?" she asked him.

He thought for a moment. "In an adult who's in their prime, I'd say about 70, maybe 80. In a child your age, about 5."

She narrowed her eyes. "Why do you have that smile on your face?" she asked suspiciously. He chuckled. "You are only five years old; but you have 95 circuits."

Her eyes widened. "Is that good?" she asked hesitantly. He laughed. "It means that you'll be the most powerful Magus ever in recorded history! The Clock Tower is going to have a field day with this!"

Helena smiled widely. "So Mother and Father were wrong! I do have magic! Just not the same one they do!"

The old man smiled. "Exactly! Now, the reason I am telling you this is because I want you as my apprentice!"

Helenas eyes widened. "You do?" she asked, in awe. He nodded, standing up and holding out a box. "My name is Kischur Zelretch Schweinorg, master of the Kaleidoscope. However, you can call me Zelretch."

Break

Helena spent three years training under Zelretch, learning the Kaleidoscope from the inside of her bedroom.

"Once you master it, you can bypass the Potter family wards and visit anywhere in the world!" he had told her.

With that in mind, Helena put her all into learning the Kaleidoscope, hoping to, as soon as she became a master, travel the world and learn the different magics the world had to offer.

Zelretch had once told her that a Magus goes through six magical inheritance's during their teenage years. She passed the first one on her eighth birthday, which brought her Magical Circuits up to 178. the next ones would be on her tenth, twelfth, fourteenth, sixteenth, and eighteenth respectively. Thinking on how powerful she'd gotten with only one inheritance, she wondered just how powerful she'd be in the future.

Either way, she had just mastered the Kaleidoscope, and Zeltretch finally let her open the box that he'd handed her the day she'd met him.

"What is this, Zelretch?" she asked him, staring at the green sceptre-like creation in the spruce box.

He grinned. "That, my child, is a Kaleidostick. It's name is Emerald."

She blinked, staring up at him. "Is it like that Mystical Girl creator you've got? Ruby, was it?" she asked in monotone.

His grin widened. "Oh, yes! Only this one is much more compliant. Ruby hates its master, however this one isn't sentient like Ruby. When you aren't using it, it'll turn into an earring."

Helena picked it up carefully. "I know how it works, however I don't think I'll use it for a while. I don't feel like I'd need to."

He nodded. "It's entirely up to you. There is, however, another part to your 'graduation' gift."

She looked at him, "what else is there?"

He smirked. "I spoke with the Clock Tower, and they gave me the go-ahead to make you a Dead Apostle."

He cringed when she squealed. "Really? I get to be a Dead Apostle?" she asked loudly.

Zelretch nodded. "You'll continue to age until you reach your last Inheritance, and then you'll never age again. Very few things can kill an Apostle, so you'll probably live until the end of time. However, due to you having so many circuits, there is a problem."

Helena frowned. "What do you mean?" she asked. Zelretch frowned. "I gave you the 'talk' last year, remember?" he asked. Helena nodded. "Well, due to the amount of power you have, you're going to need several... lovers the keep your magic in check."

Helena cringed. "Like a harem?" she asked. He nodded. "In truth, it isn't all that bad. Magi in general are very sexual beings, and Harems are not all that uncommon. Having one due to how much magic you have is actually a good thing. It is, however, necessary that you love all of those within your harem, and that they love you back."

Helena sighed. "How will I know that they love me?" she asked. He smiled, kneeling in front of her. "You'll feel it with your magic. It's part of being a Dead Apostle." he replied.

She smiled at him. "Thank you, Zelretch!" she said softly, hugging him. He returned the hug, smiling lightly. Releasing her, he said, "Now, child, you've reached your first magical inheritance. You've probably noticed that the urges to find the first man in your harem have already started, even at such a young age. With the Kaleidoscope, you can search all over for him. I suggest that you apprentice under other mages during this time, as the more magic you know the more powerful you are. Stay safe, my child."

And then he was gone, with only a large vial of crimson red blood in his place.

Helena smiled, uncorking it. "Immortality means nothing if I'm alone the rest of my life," she whispered, downing it in one go.

That night, a new Apostle was reborn.

Break

After setting up an alarm on the door to her room in Potter Manor, in case someone went looking for her (unlikely as it was, she wasn't taking any chances), Helena used the Kaleidoscope to teleport herself to Germany, where Zelretch had once told her the Einzbern family resided, a letter of recommendation from Zelretch in her hands.

The Einzbern family was well known for their Mastery in Alchemy, as well as their near-perfect Homunculi. If Helena learned how to do what they had done, she could prove to other magi around the world that she was not only intelligent, but a worthy apprentice, and possibly a future master in the subject.

She walked up to the Bounded Field that surrounded the land owned by the Einzbern family, and clutched her winter coat closer. Germany was cold, however she hoped to get used to the cold eventually.

As she reached the Einzbern gate, she saw a homunculus waiting for her.

"What do you need with the Einzbern family?" she asked. Helena bowed to her. "Greetings, Einzbern servant. My name is Helena Lilian Potter, former apprentice to Kischur Zelretch Schweinorg, the Wizard Marshall and Master of the Kaleidoscope, and newly appointed Dead Apostle. I wish to speak with the head of the family, Jubstacheit von Einzbern, about an apprenticeship."

The homunculus nodded. "Please, follow me, Lady Potter. My name is Chloris."

Helena followed Chloris into the estate, making sure to keep close so as to not become lost in the forest surrounding the palace. "The grounds are beautiful, Chloris. Do the Homunculi upkeep them?"

Chloris nodded. "I am in charge of the gardens, as well as the front gate. There are currently fifty Homunculi who work at the estate. Lord Jubstacheit is a very kind master."

Helena smiled. "I can't wait to meet him; I've heard only good things about the Einzbern family."

They chatted idly for a while more, but as they reached the palace at long last, Chloris bowed to her. "Lord Jubstacheit is waiting for you inside, Lady Potter. I hope your meeting is fruitful."

Helena thanked the girl, and entered the palace with grace.

She took one look at the old man who awaited her beyond the doors and dropped to one knee, bowing her head deeply in respect, and placing her right hand over her heart in a fist. "Greetings, Lord Jubstacheit von Einzbern. I hope you are well?"

Lord Jubstacheit laughed. "Stand, girl, no need to kneel to me. And, yes, I am well. I hope you are as well?"

Helena rose from her position. "I am, thank you, Lord Jubstacheit."

He waved her forward, and she walked up to him. He kissed both of her cheeks lightly, and she returned the gesture. "Thank you for welcoming me into your lovely home, My Lord," she said to him with a smile. He laughed.

"Any apprentice of old Zelretch is welcome anytime, child!" he replied. "I see you have a recommendation letter from him?"

She handed it to him. "I do, Lord Jubstacheit. I have recently mastered the Kaleidoscope, and with to next apprentice under a master alchemist such as yourself."

As they walked to his office, Lord Jubstacheit nodded. "I have no problems taking you on as not only an apprentice, but as an honorary Einzbern as well, should you master the art of alchemy. There are very few alchemists outside of our family, and we would like to keep it that way, you see."

Helena nodded. "I understand, and I also see no problems with it."

Lord Jubstacheit hummed. "I would also like you to apprentice under my son in-law as well. You may know his name; Kiritsugu Emiya."

She looked at him. "The Mage Killer?" she questioned. Lord Jubstacheit nodded. "He recently had a child with my daughter, Irisviel. He is retired, but I know that he had wished to pass down what he knew to another."

Helena nodded. "It would be useful to learn his craft. I hear that his Origin Bullets were unstoppable."

Lord Jubstacheit nodded. "His two Origins, 'Severing' and 'Binding' allowed his bullets to destroy any magic in their way."

She smirked. "I am in possession of more than two Origins, Lord Jubstacheit, if it is of any use to you."

Lord Jubstacheit blinked. "My, I knew you were powerful, but I wonder just how so. Do you mind if I am told the nature of your Origins, Lady Potter?" he asked.

She shook her head. "Not at all, Lord Jubstacheit. After all, if I am to be your apprentice, you would soon find out anyway."

She held up a finger for every origin she mentioned. "The first one is 'Spear'. Using it, I can not only use any weapon in the Spear category even without training, but I can also recreate them using my magic. The second is 'Severing', like Kiritsugu's is. Thirdly, is 'Poison', which allows me to consume anything potentially lethal to others and use it against them. And, lastly, is 'Time', which allows me to alter the flow of time in my favor."

Lord Jubstacheit laughed. "Four Origins! A powerful young lady you are, Lady Potter! And, what of the elements?"

She smirked. "You've heard of the forgotten elements, yes?" she asked. Lord Jubstacheit nodded. "I possess six elements in total, three of which are forgotten ones. Fire, Wind, Void, Ice, Shadow, and Lightning."

Lord Jubstacheit let out a loud bark of laughter. "You truly are something, aren't you, Lady Potter?" he chuckled.

She smiled. "I've been told so by Zelretch many times over."

"Grandpa?" a small voice called out.

Lord Jubstacheit and Helena turned to see a small girl, about five years old, staring at them. "Illyasviel, this is my new apprentice, Helena. Helena, this is my granddaughter, Illyasviel."

The small girl waved shyly, and Helena melted. She knelt down, holding out her hand. "Hello there, Illya."

The girl blinked. "Daddy calls me that," she mumbled. "Can I call you that, too?" Helena asked. Illya nodded. "Yeah!" she smiled.

Lord Jubstacheit patted Helena on the shoulder. "We will start tomorrow. I will speak to Kiritsugu about the apprenticeship. Why doesn't my granddaughter show you around the estate for now?"

Illya cheered, and Helena couldn't find it in herself to argue.

Break

"Adjust the hold there, otherwise you might shoot someone accidentally."

Helena loosened her grip slightly, earning her an approving grunt from Kiritsugu. "Better. Now, your aim was lacking the other day. I want to see how much you've improved since then. Shoot the target. I expect a perfect shot."

Kiritsugu is always such a hard-ass, Helena thought, taking a careful aim. She had the target in her sight, and she hoped to hit the middle.

Bang!

The bullet tore a small hole into the tarp they were using as their target, hitting the red bulls-eye dead on.

Helena let a smile cover her face, eyes alight in happiness. "I did it!" she cried.

Kiritsugu nodded. "Yes, you did. I see that the training finally paid off. It's been an entire year, after all."

She stuck out her tongue at him. "I've been nothing but a good student, and you know it!"

Kiritsugu laughed, clutching his gut. "I won't deny it, however you still have a ways to go before you get your own Origin Bullets and the gun to go with them."

Helena pouted. "I know. But I'm hoping to finish this apprenticeship before my next inheritance! Lord Jubstacheit told me I only had a few more months before he names me a Master Einzbern Alchemist!"

Kiritsugu smiled. "After that creation you made, you deserve it."

Helena blushed. "I only took the idea from the wizarding potion Skele-Grow. Who knew the Magi version I created would be that powerful..."

He patted her on the back. "Thanks to you, I feel much better, and I probably won't die at an early age. Losing more than half of my ribs to make the Origin Bullets would have caught up to me in a few years. Now, though, I can make as many as I want and my ribs will just keep growing back."

She smiled. "I'm glad I could help." she thought for a moment. "Lord Jubstacheit wants something original for my final project, though, so I better get cracking." then, her eyes lit up. "I got it! I have to go, Teach! I have a project to start!"

And so, she ran off toward the Alchemy Labs.

Kiritsugu stood there, a smile on his face. Behind him, Irisviel wrapped her arms around his waist. "She's such a good girl, so pure." she whispered. Kiritsugu nodded. "She's like a second daughter," he replied, clutching her hands that were wrapped around him.

"Father said that once her Mastery is complete, we could adopt her," Irisviel whispered. Kiritsugu's eyes widened. "Really?" he asked, excited. Irisviel let go of him, and danced in front of Kiritsugu. "Yes, he said that he's too old to adopt another child, and since I'll be the head of the family once he passes, it's only fair that she be the first we adopt into the family. The Einzberns have a long history of adopting Alchemists into the fold, after all."

Kiritsugu kissed her softly. "Illya will be happy," he stated, "she loves Helena like a sister."

Irisviel smiled. "She is such a kind girl. How her family could ignore her like that simply because she isn't like them..."

Kiritsugu wrapped an arm around her carefully. "She has us now, Iris."

And that ended the conversation.

Break

Lord Jubstacheit smiled warmly at his pupil. "So, this is your final project?" he asked, looking into the diamond cauldron where a shimmering red stone lay.

Helena nodded. "I remember you saying once that Irisviel and Illya both had the same defect, and that they would die sooner than they should. I made this to cure them on any impurities from the experiments done."

He hummed. "But why is it a stone?" he asked, intrigued.

She fidgeted. "I may have accidentally made the Philosophers Stone..."

He blinked. "You mean to tell me that you figured out the recipe for the Stone all Alchemists have tried and failed to create throughout the ages?"

She looked down. "I researched several attempts from over the centuries, and altered them slightly, and I think I managed it. I has all the properties of the original stone, which was destroyed over 2'000 years ago, and when I accidentally dropped a piece of paper in there, it turned into this..."

Lord Jubstacheit looked at her hand, and saw a small lump of gold.

"Try dropping another piece in there," he said. She grabbed a paper and folded it, then dropped it into the cauldron.

It turned into a larger lump of gold.

"Incredible!" Lord Jubstacheit shouted. "You've made the legendary Philosophers Stone!"

Helena smiled. "Using the liquid it excretes – which I believe is the Elixir from the Legends – we could heal Irisviel and Illya, can't we?"

Lord Jubstacheit nodded, then turned to one of the homunculi in the room. "Fetch my daughter and granddaughter! Kiritsugu as well!"

If this worked, he wouldn't have to bury anymore of his family because of the alterations. He already had to bury his wife.

At the end of the day, Helena Lilian Potter became a Master Alchemist, and was given by Irisviel and Kiritsugu the secondary name and title of Ulrika Imelda von Einzbern.

Not even a week later, Kiritsugu granted her her mastery in the form of Origin Bullets, made from her own bones, and a beautiful black trench coat with grey lining.

With two new masteries under her sleeve, and a promise to visit over the weekends, Helena decided to travel the mundane way, and headed to Japan to gain a new mastery in the field of Jewel magic, a recommendation letter from Lord Jubstacheit in her hands addressed to Tokiomi Tohsaka.