"I don't understand!"

Narcissa Black slammed shut her arithmancy textbook and flung it across the library desk, "it makes no sense! No sense at all!"

Andromeda Black snorted, conveying her own amusement at her sister's dramatic outburst, "I honestly don't know why you picked it Cissy, it's such a load of codswallop."

"Yes, well you could have warned me!" hissed Narcissa as she collected her quill which as a result of her outburst had been knocked under the desk, "If I had known arithmancy was impossible I might have actually considered studying divination! At least Bella could have given me a hand with that."

"Hah! Bella give you a hand? I'd like to see that!" Andromeda raised her eyes at her sister, before returning her attention back to her own essay. Another two inches or so on the importance of powdered unicorn horn and her essay on the draught of peace would be done, and thank Salazar for that because potions was by far Andromeda's least favourite subject.

"I don't understand the point of this stupid subject at all! I mean when ever am I going to use it? It's possibly more pointless than Muggle Studies and that is saying something!" Narcissa huffed and glanced at the sun setting outside the library window, what she wouldn't give to be one of those students lying on the grass outside.

"You should have done care of magical creatures; I mean sure you have to deal with Professor Kettleburn and the occasional bite or scratch but overall it's pretty easy and you're always guaranteed to scrape at least a pass mark."

"You might enjoy battling the elements and dealing with foul, dirty and stupid critters Andie, but I certainly don't. Arithmancy might be completely ridiculous and confusing but at least it's taught in a classroom."

Andromeda snorted once more, "well then, don't complain to me about arithmancy, after all you did have other options."

Narcissa collected her quill and textbook and resigned herself once more to her own essay, it was due Monday morning and there was no way she was going to spend her entire weekend working on it; she was determined to finish it tonight even if it meant missing dinner and working straight through the night.

"You know, I think I remember Crescencia Crabbe telling mother that Marriner received an O in arithmancy for his OWLS last year, perhaps you could ask him to give you a hand?"

"Marriner Crabbe getting an O in anything is hard to believe, let alone arithmancy! Thanks anyway but even if Marriner was any good I think I'd prefer to struggle with it myself than spend an afternoon having him flirting and leering at me."

Andromeda laughed, Marriner's affection for Narcissa was well known within the Slytherin house, and it was often a cause of great embarrassment on Narcissa's behalf, "well it was just a suggestion, and I bet he would leap at the chance to help."

"I bet he would, which is exactly why I would never ask him. Thanks though, I guess if I get completely desperate it could be a ...option."

Andromeda laughed though before she could offer a witty reply, she was interrupted by a boy she recognised from her own year group... someone Tonks?

"Sorry, I don't mean to interrupt but do either of you have a spare quill? Mine just broke and I can't fix it and desperately need to finish this essay before 5."

Ted Tonks held up his broken quill as if indicating the desperation of his situation.

Narcissa, who'd never seen the boy before, looked him up and down, immediately recognising his prefect badge and Ravenclaw robes. If it wasn't for his untended to mop of fair hair he wouldn't be half bad but given she had never crossed paths with him before now she was sure he was definitely a half-blood, or maybe worse, muggle-born.

Andromeda, slightly taken back from the interruption, quickly regained herself, "I don't have another one, I'm sorry. But I'm almost done so I guess you could have mine once I'm finished."

Ted glanced around the almost bare library, he'd already asked most of the students already and the old cranky librarian Mrs Kincumberan had shooed him away when he'd asked her a second time to please check her desk drawers; he wasn't too fond at the thought of heading to the Ravenclaw tower on the other side of castle to sift through his trunk or search the castle for some friends so the option offered by the Slytherin girl was perhaps the best he had.

"That would be great. Thank you."

Andromeda nodded, "I only have another two inches to go, so I shouldn't be long."

Andromeda returned her attention to her textbook sifting through the pages and began copying word for word, Slughorn wasn't likely to care too much – he always favoured Slytherin students anyway or those who were in his slug club, luckily Andromeda was a member of both.

"What's your essay on?" asked Narcissa who welcomed the distraction Ted offered from her own work.

Ted who had turned on his heel to fetch his books with the intention to settle at a desk nearby stopped in his tracks, "Oh umm, it's on the magical properties related to the numbers 8 and 9 and how they have evolved since medieval times... it's for arithmancy."

Narcissa's ears perked up immediately, "You do arithmancy!?"

Ted smiled slightly, "Yeah I know, it's a bit nerdy but I kind of enjoy it."

Andromeda raised her eyes slightly at her sister with a knowing smile on her face, any moment now Narcissa would be turning on that famous charm that no man could resist.

Sure enough within seconds Narcissa had rearranged herself, instead of being slumped over her textbook she was now leaning gracefully against the wall, one hand wrapped across her lap the other outstretched on the desk, and her eyes focussed upon Ted, her head tipped slightly... "Oh no that's not what I meant at all. I do arithmancy as well; it's what I'm working on right now in fact, except I'm having a few difficulties."

"Oh?"

Sure enough Ted Tonks had fallen victim to Narcissa's infamous charms. Andromeda rolled her eyes, and focussed on the last couple of lines of her essay, she could tell what was going to happen here.

"Yeah I just... well it just doesn't seem to make much logical sense to me. I mean I know you have your own work to do but you don't think you could give me a hand do you?"

Ted glanced quickly at his watch, it was 10 past 4 already and he had to have his essay completed and handed to Professor Hardwicke by 5 on the dot. Surely though he could help the girl at the same time, "I could try."

"Excellent! Oh thank you so much!"

Narcissa motioned to a chair at a nearby desk, indicating him to pull it over and she flipped her textbook to the graph of numbers that had been troubling her for the past hour, "While Andie wraps up her essay perhaps you could tell me what in Merlin's name this is all about?"

Ted glanced at the page the girl was pointing to and smiled slightly, "Oh you're a third year then? This is basic stuff once you can wrap your head round the Nelthora formula... can I borrow your quill for just a moment?"

Narcissa handed Ted her quill, hoping this wasn't some kind of a ploy so he could run off and do his own essay but sure enough it wasn't and Ted began jotting a long mathematical equation above the graph in her textbook, "See this here? This is the Nelthora formula, in order to interpret the graph you have to divide all the numbers by the number aligned with their magical property and then apply that number you get from doing that to the Nelthora Formula, does that make sense?"

Narcissa stared at the page in front of her wondering how on earth she would ever have worked that out on her own, "sort of...so I take this number here and divide it by its magical property number and then use that in this formula here...?"

"Precisely" stated Ted, relieved that his babbling had actually made sense, "see here, take number 9 for example we know from Wenlock's theory on the magical property of numbers that 9's magical property number is 3 because it is divisible by 3, so you take 9 divide it by 3 which obviously gives you 3 and then substitute 3 into Nelthora's..."

"I'm done!"

Andromeda slammed shut her potions textbook and flicked her quill toward Ted, "there you go you can just pass it on to Narcissa when you're done with it."

Ted who had momentarily forgotten about his own essay looked slightly taken back though quickly remembering his own work lying abandoned on a desk nearby, leaped up, "Thank you, ummm Andie was it?"

Ted had seen the girl before, she had definitely been in his charms class as he had vivid memory of her being the first of his classmates to turn her goblet into an apple in second year, though despite this he had never spoken with her before nor paid her much attention.

"Andromeda", corrected Andromeda, Andie was a name used only by her close friends and family, "Andromeda Black", she said her last name with great emphasis partly out of habit, but also in an attempt to remind this boy of his place – though it was likely he was so ignorant he wouldn't even know what such a last name conveyed.

"Andromeda, sorry", replied Ted, clearly unfazed by the mention of her surname, "Thanks a lot, I really appreciate it."

Andromeda gathered her books and gave her sister one last glance, "It's fine. Tonks isn't it? Well, like I said just be sure to pass it on to my sister when you're done. I'll see you Narcissa."

Narcissa gave her sister a small wave as Andromeda turned to leave, "I'll catch you in the common room later."

Andromeda smiled to herself, she had no doubt Narcissa would be in the common room later, with Ted Tonks and his infinite arithmancy knowledge Narcissa's assignment would surely be finished before dinner. How typical, thought Andromeda, things always seemed to work out for Narcissa...