A/N: Sorry, I have to whiz through the first few years of Harry's life then skim over his school years until I can get to the juicy stuff Post-HBP. I'll do my best to make it as painless as possible!

Disclaimer: I unfortunately do not own anything in the Harry Potter world. It all belongs to J.K. Rowling. Except for Jessie – she's all mine!

Prologue:

Darkness. Warmth. Weakness. Struggling. Embraced. Love. Reassurance. Trust. Two merge and become one.

Big green eyes look steadily into cold blue. A cooling body lay limp on the floor nearby, red hair falling gently into glazed green eyes. A shield of love surrounds the child, ancient and powerful. A high-pitched laugh and the Dark Lord spits out the words of his downfall, "Avada Kedavra!"

A searing green light carves into the child's forehead. Warped by Love, it awakens rather than kills. Together, Love and the woken presence spit the curse from the child's body and back at the caster.

Power the Dark Lord knows not.

A three-year old Harry lay quietly in a dark cupboard, his tiny hand pressed to a painful lump on his head where he had collided with his Aunt Petunia's frying pan. His little stomach gnawed with the familiar pang of hunger, and silent tears rolled down his pinched cheeks.

Harry.

Harry jumped and winced as he had pushed a little too hard on his tender head.

"Who's there?" he whispered, clutching a dingy blanket to his chest.

It's me.

Harry furrowed his brow in confusion. He knew he heard a voice, but he was pretty sure he hadn't heard it with his ears. "Who are you?" he whispered.

You.

"Huh?"

Harry heard a childish giggle. I'm you and you're me.

Sensing his growing confusion, the voice continued, I'm in you.

Harry looked down at his stomach, horrified. "I ate you!" The little voice was so amused Harry felt a huge bubble of laughter threatening to pop out of him. He clapped his hands over his mouth and shook with quiet giggles. Harry was in awe of this happy feeling. Happiness was a distant memory for him – something he associated with round glasses and red hair.

As the laughter slowly subsided, the voice asked, What're you gonna call me, Harry?

"Whaddya mean?"

Well, I'm a girl. You can't call me Harry.

"Oh." Harry thought really hard about girl names, but the only girl he knew was Aunt Petunia and he didn't want to call his new friend that. As he thought harder, he suddenly remembered a shopping trip he took with Dudley and his Aunt last week.

They were at the supermarket. Dudley was in the child seat of the shopping cart and Harry had his fingers curled in the holes on the side of the cart. As Aunt Petunia pushed past a shelf of office supplies, Dudley flailed his arm out and knocked over a box of pens. An exasperated Aunt Petunia had snapped, "Harry, pick those up!" Knowing better than to argue, Harry had crawled on the floor, picking up as many pens as he could find. Just as he was dumping them back into their box, a two-year-old girl with flaming red curls toddled over and shyly handed him a pen he had missed. "Thank you," Harry smiled at the girl as she grinned and stuck two fingers in her mouth. "Jessie, come on," the girl's mother called. Little Jessie waved bye-bye as Harry handed the box of pens to Aunt Petunia to put back on the shelf.

"Jessie," Harry said.

Okay. Harry sensed a smile. Suddenly his little tummy gave a mighty growl, once again bringing tears to his eyes. He was so hungry!

Let's get food, Jessie said.

"But the door…" Harry glanced at the locked cupboard door.

Pretend it open. Harry was a little unsure what to think of that, but he decided to try. He looked at the door and remembered all the times it was open and began to pretend it was open now. As he reached out his hand and touched the door, he heard the bolt slide back and the door swung gently open. Harry gasped.

See? I knew you could do it!

Harry cautiously poked his head out and looked toward the kitchen. All was quiet as he crept to the pantry to nick some food. His young mind realized a whole new world was open to him now that he had a secret friend and he could pretend his way out of his cupboard for food. A smile lit up his face and he was thankful for Jessie.

Over the years Harry and Jessie became close friends. Harry was glad to have her with him when his Aunt and Uncle would berate him and call him a "worthless freak." She would always comfort him, telling him he was special and that she loved him – for they had long since decided they were siblings. As of yet they had no idea of how or why Jessie was in Harry's head, they simply accepted it and were grateful for each other's company.

Their introduction to the wizarding world was exciting. The explanation that magic really does exist was a relief for Harry. He finally realized that he's not a freak – there are others just like him. It was also a relief to know their parents were not unemployed drunks who died in a car crash as they had so often been told. They were actually well-loved and regarded somewhat as heroes. It was, however, disconcerting to discover that Harry was also famous and known as the savior of the wizarding world. No pressure, Harry. Jessie had commented somewhat sarcastically.

While they were in Diagon Alley with Hagrid to buy Harry's school supplies, Harry became especially interested in the book store. He and Jessie were still curious about her presence and figured it must have something to do with magic. However, Harry did not want to lose his first friend (besides Jessie, of course) by purchasing books about hearing voice in one's head. He was already a freak at home – he didn't want to be one in the wizarding world too. So he let that opportunity pass and simply hoped for another chance to look through some wizarding books while alone.

Because of Harry's rather secluded and neglectful upbringing, he had never really had the opportunity to make any friends. He was thankful, therefore, for Jessie's aid. While she had naturally had the same upbringing as he, except from a slightly different perspective, she was female and had that innate intuition about people that girls seem to have in spades and boys dismally lack. It was surprising, then, that Harry's first friend after Hagrid was made by himself. While standing in King's Cross Station, clueless as to how to get on a platform that didn't seem to exist, Harry was drawn toward a small sea of red-heads. As he crept closer to the family, he caught words, such as "Muggles" and "Hogwarts" that made him realize they were also wizards. Feeling so comfortable with the kind-hearted mother of the pack, Harry recalled fleeting images of his own red-haired mother and wondered if she would have been anything like this kind lady had she lived. This was why Harry was so eager to get to know Ron Weasley when he asked to share his compartment on the train.

Hermione Granger's friendship, however, came with Jessie's help. Harry was as ready as Ron to write her off as a bossy know-it-all after her first visit to their compartment on the train. But just as that particular thought was ringing through his head, Jessie cut in, She's scared.

What? He thought back.

She's scared. She said herself she's a Muggle-born and didn't know about magic until recently. Her obsessive studying and need to know what's going on around her means she's afraid of rejection in the wizarding world. So, simply put, she's scared.

How do you know these things? Harry was baffled.

I'm a girl. I'm perceptive.

Geeze.

After that, Jessie left him alone for the train ride, but Harry decided to give Hermione a chance. Although it wasn't until a certain escapade with a mountain troll that she officially became a part of the group.

During the course of their first year, the trio and Jessie became increasingly interested in the mystery surrounding Hogwarts. While the others were convinced Snape was after the Sorcerer's Stone, Jessie wasn't so sure.

I really don't like Quirrel, Harry.

Why? He had asked. He's perfectly nice. Nervous, but nice.

There's just something off about him. Something almost fake. At Harry's protests, she continued, And I don't like how you always get headaches near him – especially when his back is facing you.

Maybe I'm allergic to garlic. Harry had tried to reason, referring to the strange smell coming from Quirrel's turban.

I doubt it. Jessie had responded, but she let the subject drop.

It was with some degree of smugness, though, that Jessie had whispered I told you so to Harry when they discovered it had been Quirrel after all. Harry had snapped Shut up before their attention was focused on staying alive and keeping the stone from Voldemort.

During the summer before their second year, Harry and Jessie had a horrible time at the Dursley's. Dobby the house-elf showed up and dropped a pudding on Mrs. Mason's, the wife of an important client of Uncle Vernon, head which consequently led to a letter from the Ministry of Magic being delivered stating that Harry was not to be doing magic over the summer. As Uncle Vernon read the letter, a nasty grin forming on his piggish face, Jessie had been fretting, Oh no, oh no, oh no! We are in sooo much trouble! Oh Harry! Harry tried to remain calm, but began to worry almost as much as his sister as Vernon grabbed his arm in a strong grip, sure to leave bruises, and hauled him up the stairs.

The next day when Harry found himself locked in his room with bars on the window, five bolts on the door and a tiny cat-flap to retrieve small portions of food from, Jessie cried. Harry sat, stone-faced, staring at the wall, listening to his sister sob in his head. Some of her tears leaked out of his eyes and down his cheeks, but he made no move to wipe them.

For three days they lived locked in the room, until on the third night, the Weasley boys showed up in a flying car. Barely escaping Uncle Vernon's clutches, Harry was whisked away to The Burrow to spend the rest of the summer.

During the school year, they were swept into another mystery. During a particularly dull detention of answering fan mail with "Professor Fairy-Face" as Jessie had so dubbed Lockhart, a voice had hissed, "Come…come to me…Let me rip you…Let me tear you…Let me kill you…"

Jessie, please tell me that was you and that you're joking. Harry pleaded silently.

Of course that wasn't me! She snapped, scared. That has to be the most terrifying thing I've ever heard!

Harry and Jessie continued to hear the disembodied voice hissing murderously around the school and they found, along with Ron and Hermione, Filch's cat petrified. When questioned, all were hesitant to mention Harry hearing the voice. Later, when Harry asked his friends if they thought he should have told the professors about the voice, Ron had immediately answered, "No. Hearing voices no one else can hear isn't a good sign, even in the wiazrding world." Harry sensed Jessie's unease and tried to reassure her, but he was inwardly glad he had never mentioned Jessie to anyone, even Ron and Hermione. They would think he was mad.

After discovering they were Parslemouths, finding Tom Riddle's old diary, saving Ginny from the Chamber of Secrets, battling a basilisk, destroying the diary and freeing Dobby from the Malfoys, Harry and Jessie were almost glad the school year was over. Except for the fact they had to return to the Dursley's and their hellish room.

Summer at the Dursley's was awful, but not as bad as it could have been as Harry was not locked in his room all hours of the day. The bolts remained on the door and the bars on the window as a warning to him, should he cross the line. Harry did his best to stay on the Dursley's indifferent side (as he would never be on their good side as long as he lived). He did sneak his homework into his bedroom, hiding it under a loose floorboard and working on it at night. But he was careful not to get caught.

It wasn't until Aunt Marge came to visit that all hell broke loose. Most of her visit went by relatively smoothly with Jessie drowning out her insults to Harry as she always did when Marge began to badmouth him. It was the last night of her visit, though, that it happened. Marge, a little heavy on the brandy, opened her fat mouth and spoke ill of Lily Potter.

"…you're sister was a bad egg. They turn up in the best families. Then she ran off with that wastrel and here's the result right in front of us."

As she was speaking, Jessie started speaking louder and louder until she was yelling in Harry's head, You good for nothing fat COW! HOW DARE YOU INSULT MY FAMILY? YOU LOOK LIKE A MAN-PIG STUCK IN A DRESS! YOU'RE DOG'S A MANGY MONGREL THAT OUGHT TO BE PUT DOWN! I HOPE YOU FALL ON YOUR FACE!

Harry's eyes glazed over as he listened to Jessie's rant and did his best to ignore Marge's preaching of his bad blood. When Marge inquired about James Potter's occupation and Uncle Vernon replied that he was unemployed, she slurred, "As I expected! A no-account, good-for-nothing, lazy scrounger who – "

Cutting like a knife into his heart, Harry had enough. He began contradicting Marge. She antagonized him further and Uncle Vernon frantically tried to get the conversation back under control. Jessie, meanwhile, was swelling with anger inside of Harry. How dare she speak of her parents and her brother in that manner?

"They died in a car crash, you nasty little liar, and left you to be a burden on their decent, hardworking relatives! You are an insolent, ungrateful little –" Marge's words were poison, they hurt so.

Jessie snapped. A wave of magic burst from her, channeled through Harry and attacked Marge, causing her to swell like a balloon and float to the ceiling. Harry took it as his cue to leave. His and Jessie's anger combined caused the cupboard door to slam open, revealing his trunk which he grabbed. As he was moving through the house gathering his belongings, Petunia, Vernon and Dudley were afraid, for Harry's anger was palpable, prickling at the back of their necks.

One wild ride on the Kinght Bus later, Harry found himself being scolded by the Minister of Magic and given a room in The Leaky Cauldron. He and Jessie now had two weeks to themselves in Diagon Alley.

Harry made use of this time by finishing up school work, visiting shops and looking through the book store. Because the school years were always so eventful, he had never had a chance to research his and Jessie's condition. Perusing the shelves of books at Flourish and Blotts, Harry finally found what he was looking for on a dusty shelf in a dark corner of the shop. A black leather-bound book with a crusty, cracked spine caught his eye, Voices in the Mind by Anonymous. Harry pulled down the book and sat on the floor, leaning against a wall. He scanned the table of contents and found what he was looking for in Chapter 13: Two Persons in One.

Vanishing twin syndrome is the identification of a multifetal gestation with subsequent disappearance of one or more fetuses. The rate of multifetal gestation at conception is higher than the incidence noted at birth

In vanishing twin syndrome, there may be complete reabsorption of a fetus, formation of a fetus papyraceus (ie, a "mummified" or compressed fetus), or development of a subtle abnormality on the placenta such as a cyst, subchorionic fibrin, or amorphous material.i

The embryos of the dead twin may become incorporated into the placental membranes. The surviving twin may occasionally display congenital abnormalities. When one twin dies later in pregnancy and the gestation continues for sometime, the water of the dead twin's tissue may be reabsorbed and the dead fetus can become flattened from pressure of the growing twin. The most widely discussed consequence of twin death is the possible occurrence of widespread damage in a surviving twin not only physically but also emotionally. Dr David B Chamberlain, psychologist, states that the earlier a fetus, infant is subjected to pain, the greater the potential for harm. Pain makes deep impression on fetuses and babies. The younger the person the more impressionable and damaging the pain, anger, grief, loss may become.ii

Though it has never been tested, some wizard psychologists theorize that in the event of a vanishing twin having been absorbed by its superior sibling during gestation, if both mother and twins were magical, the missing twin may be reawakened in the mind of the superior by means of a powerful dark curse.

Harry set the book down in his lap, thoughtfully.

Well,. Jessie said. I think that about sums it up.

"No kidding," Harry whispered. He pulled out a parchment and quill and began diligently copying the passage he just read. There was no way in the wizarding world he, the "Boy-Who-Lived," was going to be caught purchasing a book called Voices in the Mind.

On the train ride to Hogwarts, Harry and Jessie had their first encounter with a Dementor. It was a terrifying experience involving a jumble of sounds and emotions in poor Harry's head, for it seemed their worst memories were not identical. After continued exposure to the Dementors, they began to sort out what was what. Harry's memory was of Voldemort murdering their parents, while Jessie's was of awakening in Harry's mind. Harry discovered the awakening was a painful process for Jessie. Her memory began with a loud rushing sound and blinding green light whirling around her form. Then came the sensation of being ripped apart by every extremity and a scalding jagged line being carved on her (or was it his?) forehead. The memory ended with her, with the help of another comforting presence, brutally forcing the agonizing light away.

Harry and Jessie realized this was the experience of the Avada Kedavra curse, surely the most powerful dark curse, waking her. But the effort of pushing it out, they speculated, caused her to sleep for nearly two years.

Another exciting year at Hogwarts; their third year brought Professor Lupin, Sirius Black, Scabbers / Pettigrew, the Marauders Map, Buckbeak and a time turner.

Harry and Jessie were overjoyed to learn they had a godfather and wrote to him often during the summer before their fourth year.

Their fourth year was tough as they struggled with visions, scar pains, rising action from the Death Eaters and the Tri-Wizard Tournament.

At the end of the third task, when Harry and Cedric grabbed the cup only to be transported to the graveyard of Little Hangleton, Jessie and Harry witnessed the murder of Cedric and the rebirth of Voldemort.

During the duel with Voldemort when their wands connected, it was Jessie who gave the extra push of power to Harry to keep the gold bead of light from touching his wand and sending it Voldemort's way.

It was a powerful moment when they saw their parents come from the tip of Voldemort's wand. Their forms encouraged Harry and just before he let go of the connection, Lily Potter looked straight into his eyes and said, "We love you Harry and Jessie." They distracted Voldemort long enough for Harry to grab Cedric's body, summon the cup and portkey back to Hogwarts, a broken, sobbing mess.

Even through their feelings of grief, Jessie couldn't help but feel elated and free. Her mother knew she was there!

The next summer was hard. Dementors attacked Dudley and Harry had to explain the goings on of the wizarding world to his Aunt and Uncle. Then they were escorted to Sirius' house where they were made to clean some truly nasty messes. It was during their stay at the Black house that they got some disturbing news – Snape was to teach them Occlumency. Jessie was horrified.

What's the matter? Harry asked. I thought you actually liked the evil git for whatever reason.

He may be a git, Harry, but I still don't think he's evil. Jessie replied. It was an ongoing argument they had been having since their first year. Jessie was inclined to believe the best of Snape – Dumbledore trusts him, so should you, she would scold Harry, very much like Hermione would. Harry, on the other hand, didn't like him one bit and was prepared to think the worst of him.

Well, then why are you so upset that he's going to teach us one-on-one. I thought I would be more upset, not the other way around!

Because, you nitwit, Jessie replied, he will be delving into our mind. What if he finds me? What then? Are we prepared for him to know about me?

But Jess, Harry was amazed to find himself playing the role of the calm, level-headed twin for once in his life, what if VOLDEMORT finds you?

Jessie stopped ranting and paused, even more horrified.

Wouldn't you prefer Snape to Voldemort?

Well…I…yes, of course…but…

And wouldn't you want to learn how to block Voldemort from finding you?

I…oh, Harry, you're right. I'm just so nervous!

It'll be okay, Jess. I won't let anyone find you.

I'll hide as best I can, Harry. Oh dear, this is going to be a hard year.

During Occlumency lessons, while Snape attacked Harry's mind, Harry would throw all of his defenses into protecting his sister and not worry as much about his own mind. Which, of course, led to Snape believing Harry wasn't trying at Occlumency since his mind was so easily accessible. Because Jessie made herself as small as possible in Harry's mind and didn't dare risk saying a word to Harry in Snape's presence, she was unable to mediate his thoughts and comments toward the Professor. On the whole, Occlumency became a fiasco. But they were successful in keeping Jessie hidden.

Professor Umbridge provided a whole new set of problems. During Harry's first detention with her, when he wrote "I must not tell lies" and had it carved in the back of his hand with a cursed quill, Jessie became angry.

That EVIL, SADISTIC TOAD! She raged as she felt her brother's pain. But there was nothing she could do.

They secretly defied Umbridge as she collected more power in the school by forming the DA and teaching their fellow classmates how to properly defend themselves.

Then came the Department of Mysteries. Falling into a trap, endangering friends and watching their godfather fall through the veil in the Chamber of Death was too much. When Voldemort tried to possess Harry's mind at the end of his duel with Dumbledore, Jessie did not tolerate his entrance and pushed with the same force she had used fourteen years ago to expel the killing curse. The exertion once again caused her to pass out for some time. Harry was forced to grieve alone during the summer.

Jessie finally woke again during the middle of their sixth year of school. She woke up during dinner one day while Harry was seated across from Ron and Lavender as they were in the middle of a rather grotesque snog session.

WHAT THE BLUE BLAZES? RON and LAVENDER?

Harry yelped and jumped about a mile in his seat, spilling pumpkin juice down his front and choking on pudding. The Great Hall got uncomfortably quiet as everyone turned to stare at the "Chosen One" choking and spluttering on the floor. Ginny hopped down and began thumping Harry on the back until he spit up the pudding stuck in his throat, much to everyone's disgust, and began to wheeze for breath.

"Mr. Potter! Are you alright?" Professor McGonagall was hovering over him, giving him a hand up off the floor.

"Yeah…wheeze…I'm fine, Professor…wheeze…thanks."

"Are you sure? Does your head hurt at all?" she looked meaningfully at him.

"No! No, nothing like that! I was just…startled…by something. I'm okay now though." Harry tried to ease his way out of the Hall.

McGonagall finally nodded with an, "Alright, Potter. Please be more careful next time with your pudding."

With that, Harry took off for Gryffindor tower.

Jessie!

Hi Harry!

Merlin! Are you trying to kill me!

Jessie laughed, Sorry about that. But honestly, what's Ron doing with Lavender?

Long story. Harry rolled his eyes.

A/N: I got the information on vanishing twins from an emedicine website and a vanishingtwin website. I am having the WORST time citing my sources here so this is the best I can do. Basically, I borrowed that information - all credit goes to the researchers on those sites. If you're really curious, do a google search. That's how I found them.