Chapter 1: Finding the Formula

Disclaimer: I don't own anything. All these characters belong to JK Rowling. I just like to use them for my own fantasies.

HA! That's check mate, Harry! You always walk into that trap! You owe me a box of Chocolate Frogs!' Ron was pumping his fist into the air triumphantly as Harry sat with his head in his hands, staring dejectedly at the chess board.

He sighed once. 'I can't believe it, mate; you did it again! Why did I let you talk me into a bet?'

Hermione, sitting nearby on the couch near the common room fire, looked up in annoyance at the noise both boys were making.

'Will you two please give it a rest!? Shouldn't you be doing your homework; neither of you have studied for Snape's test tomorrow, have you?' she said in a bossy tone of voice.

Both boys groaned, knowing what was coming. She wouldn't rest until they had finished all of their studying for the night.

'N.E.W.T.s are coming up in only a couple of months! You two have got to get more serious about your studies!' she said in a stern voice.

'It's only four o'clock, Hermione,' Harry said in a whiny voice. 'I promise we will study for Snape's test with you after dinner.'

'I've already studied for Defense class; you will have to study alone, Harry Potter!' she said with a huff as she turned back to her homework.

'What are you working on, then?' Ron asked as he walked towards her to peer over her shoulder. Seeing a parchment full of numbers and complicated-looking equations, he wrinkled his nose in disgust.

'I'm working on my Arithmancy homework,' Hermione said in a pleased voice. Arithmancy was by far her favorite subject, and she was close to being finished.

'Ugh, Hermione, that looks terrible! Why you are taking Arithmancy at N.E.W.T. levels is beyond me! You're mental!' Ron said as he plopped down next to her on the couch.

'Well, Ronald, at least Arithmancy is something I will be able to use. You're the one who attempted to get an O.W.L. in Divination!'

'Well, we all can't storm out of Divination after tossing Trelawney's crystal ball down the stairs, now can we?' Harry piped in, laughing. At that comment, all three members of the Dream Team -- as they were officially dubbed by Rita Skeeter since Voldemort's defeat by Harry two months prior —erupted into laughter, remembering Hermione's legendary exit from Divination in their third year.

'Don't you regret it just a little bit, Herms, after finding out that prophesies really do exist, that Divination is real?' Harry asked, after their laughter had died down a bit.

'Harry, prophesies can't be taught! I looked it up after our fifth year; you either make them or you don't. Think about it, when Trelawney did make a true prophesy, she wasn't even aware! Besides, if I want to know what's going to happen in the future, I will use Arithmancy.'

'You can tell the future using Arithmancy?' Ron asked, suddenly interested.

Hermione rolled her eyes. 'Of course, that's what Arithmancy is. It's a method of Divination by numbers first used by the ancient Greeks' she said, quoting her Arithmancy textbook. 'I can use Arithmancy to calculate percentages and trends of what might happen or how things could possibly happen in the future.'

Ron and Harry were both starting to get that glazed look in their eyes that said they didn't have a clue about what she was saying.

She sighed; sometimes it was so hard to talk to them. 'Listen,' she said, trying to get her point across. 'I can give you an example. Let's take Snape's test tomorrow.' She took out a fresh piece of parchment and started to write on it. She wrote Ronald Bilius Weasley and wrote down numbers under his name. She then did the same with Snape's name, the words Defense Against the Dark Arts, test, and tomorrow's date. Snape had been teaching them wandless magic, so she added some of the spells she was sure they would be tested on. Using the numbers she had come up with, she started to use a series of calculations and equations. Three minutes later, she looked up from her parchment.

'Okay, Ron, it says here that you have an eighty percent chance of passing tomorrow's test.'

'Really? Hey, not bad!' Ron said with a smile on his face.

'Well, it's not completely accurate. I don't know Snape's middle name, and if I knew his birthday, I could probably be more specific,' Hermione said. 'The more information I have to go off of, the more accurate the calculations are.'

'Tobias,' Harry said in a low voice.

Hermione and Ron looked at him blankly. 'What was that, mate?' Ron asked.

'Tobias. Snape's middle name is Tobias,' Harry said.

Hermione raised one of her eyebrows at this while Ron gaped at Harry.

'How do you know Snape's middle name?' the redhead asked incredulously.

'Occlumency lessons our fifth year. It was in one of his memories…. I think it's his father's name,' Harry replied.

Hermione smiled and wrote Tobias down on her parchment. She added another series of calculations to the already half full page.

When she looked up at the boys, Ron was saying something about nicknaming the Defense Professor Toby. She couldn't help but giggle at that.

'I wouldn't say anything like that in front of him, Ron. Your chances of passing just went from eighty percent down to sixty percent,' she said with a sympathetic look on her face.

'Bloody Hell, why should I even bother studying?'

'Because, Ronald, you still have a sixty percent chance. Use that to study hard and beat the odds!'

Harry rolled his eyes. 'We will both study after dinner, we promise, Herms. Okay?'

She smiled as his green eyes met her brown ones.

'Well, let's go to dinner now, since you two have managed to completely distract me from my work,' she said as she stuffed her books back into her satchel.

As Hermione sat down at the Gryffindor table between Harry and Ron, she glanced up to the Head Table. Snape sat in his seat frowning down at his plate as the newly appointed Headmistress McGonagall spoke to him excitedly. The DADA professor had changed little since the demise of Voldemort. The only changes being that he had managed to gain a few stones and looked a lot more relaxed in Hermione's eyes. Since her fifth year, she had made it a habit to check on him at every meal. After realizing his role in the fight against Voldemort, Hermione had started checking to make sure he was okay. Even now, when it was all over, she hadn't managed to break that habit, and so she still checked on the dour professor whenever she sat down to a meal. Last year, every time she had glanced up, he had looked more and more haggard and drawn as he drew nearer and nearer to the night he had been forced to kill Dumbledore.

Hermione sighed as she felt a small pang in her heart for the former Headmaster. It was still hard sometimes to believe that she would never again look up at the Head Table and see those blue eyes twinkling at her. At the beginning of their sixth year, Dumbledore had already been dying, so that when Snape had used Avada Kedavra, Dumbledore was already half-dead due to the curse inflicted on his hand that had slowly been spreading throughout his body. Dumbledore's portrait and a Pensieve had been used in the trial to clear Snape of all charges. Since Snape had used Avada Kedavra at Dumbledore's request, he avoided spending anymore time in Azkaban. Even Harry had come to terms with the fact that the 'greasy git' was truly on their side.

Hermione was drawn from her thoughts when Lavender and Parvati squeezed into the bench next to her. Her reverie was broken by the two females ordering Harry and Ron to budge over; they needed Hermione for 'girl talk.' Hermione raised her eyebrows at the girls in question; they rarely bothered to try 'girl talk' with Gryffindor's resident bookworm.

'Hermione, Parvati and I couldn't help but overhear what Ron was telling Neville,' Lavender started. Hermione had long before learned to tune most of the boys out, so she had no idea what Lavender was talking about. She waited for an explanation.

'We were wondering,' Parvati started, her voice taking on a slight whining quality. 'Could you use Arithmancy to tell us who our soul mates are?'

Hermione laughed. She should have expected a request as inane as this to come from her former roommates. She took a second to thank the gods that she had the Head Girl's room all to herself this year.

'Arithmancy isn't that specific. I can't figure out something like who your soul mates would be,' Hermione said in an amused voice.

'We could give you a makeover for… like… payment!' Parvati suggested.

'Yeah, we know loads of glamour spells that would be perfect for you!' Lavender piped in, obviously excited about the idea.

Hermione was shaking her head. 'Girls, I don't need payment; it can't be done. All I could do is calculate the chances of you finding your soul mates, and even that would be really inaccurate. The more information you have, the more accurate my calculations would be.'

Lavender pouted and blew out a breath when Hermione said this. She turned to Parvati and said, 'Well, I guess Divination is better…. I knew it. Maybe Professor Trelawney could scry our soul mates in her crystal ball.'

Parvati nodded eagerly, and the two girls left the table to find the professor and divine who their soul mates would be.

Hermione rolled her eyes as the two girls flounced out of the Great Hall.

As Hermione finished her pudding, she thought about what she had told the two girls. Arithmancy was an exact science, but it wasn't specific enough for a number of applications. I wonder if there is a way to be more specific, she thought to herself. Was there a way to alter her calculations to be more accurate?

If she could change the calculations to come up with a solid number rather than a percentage, perhaps she could use Muggle mathematics to divide that number into the separate components. If she could come up with the separate numbers, she could then match up those numbers with their possible letters and spell the correct answer out. She chewed on her lip, her pudding forgotten as she thought about this. She would come up with a number of possible answers, but it would be more specific than a percentage.

In a flurry of bushy brown curls, Hermione stood up abruptly and made to leave the table. At Harry's questioning glance, she explained that she needed to check something on her homework, and she left the Great Hall, walking as quickly as possible. She wanted to get back to her books so she could test her theory.

When the boys found Hermione, thirty minutes later, she was in the common room surrounded by Arithmancy texts and furiously scribbling notes into a Muggle notebook. While her professors would only ever accept homework on proper parchment, Hermione preferred to take notes on the lined Muggle paper of her childhood.

True to their words, the boys took seats next to her and opened their book bags. They didn't try to speak with her as they recognized the look on her face. She was deep into her research and wouldn't be coming out until she found her solution. Ron sincerely hoped that whatever she was working on wasn't another campaign like the house-elf nonsense of the previous school terms.

When Hermione finished her notes, the common room was empty. She vaguely remembered the boys calling out a good night to her as they left for their dorm rooms around midnight. Her mouth opened in a wide yawn as she looked around, wondering idly how late it was. She had come up with a viable theory, but would need to test it in the morning; she needed to get some sleep.

The next day was extremely busy for Hermione. Due to the test in Snape's class and her regular class load, it wasn't until after dinner when she had the chance to pull out her notebook again. She re-read the notes she had made the night before; her calculations made sense, and now she just needed to test them. She bit her bottom lip as she tried to decide what she should calculate first in order to test her new theory.

At that moment, Lavender and Parvati entered the common room giggling and whispering, and Hermione smiled widely. They had given her the idea, after all, and it couldn't hurt to know…. She bent down over her notebook once again and set about trying to figure out who her soul mate was.

It took about three hours to calculate all the specifics, but she was almost finished. She had finished the Arithmancy portion and had solid numbers! If her theory was correct, all she had to do was divide the numbers up using Muggle mathematics and she should have the three names most likely to be her soul mate.

As Hermione finished the math and started writing out the letters under each number, she felt the color drain from her face. She had just written the last name down: Severus Snape. She shook her head. It couldn't be him. The other names she had come up with were Stan Shunpike and Oliver Wood. She took a deep breath. It wasn't Professor Snape; that wouldn't make any sense. She thought of Oliver Wood, she remembered him from her first few years at Hogwarts. He wasn't bad. Maybe he was her soul mate. He was a Quidditch player now and quite famous.

Hermione turned to a fresh sheet of paper in her notebook. She could use traditional Arithmancy to calculate the chances each name had at being her soul mate. She started with Oliver Wood; he was the most appealing option after all. It only took a few minutes to complete these calculations, and when she was finished, Hermione looked down at her notebook with a frown. Oliver Wood only had a thirty percent chance of being her soul mate. She shrugged, she had never met Stan Shunpike, but Harry had mentioned that he was 'a decent bloke.' She started his calculations, only to feel her heart sink minutes later when she ended up with a fifteen percent chance.

Her breathing increased a little as she set about doing the calculations on the last name.

Ninety-eight percent chance that Severus Snape was her soul mate!

'No, it can't be!' she said aloud. She quickly tore out the piece of paper and threw it into the fireplace. She hastily grabbed her stuff and fled for the privacy of the Head Girl's room. Once in her room, she flung herself on her bed.

She thought of all the horrible names that Harry and Ron had called Snape at one time: 'the greasy git', 'the bat', 'the vampire'…. The list was a long one.