Chapter 7: I Solemnly Swear
"This is disgusting."
Sirius had just ushered her into the seventh-year boys' dormitory. It looked very much like one might expect a room shared by four 17-year-old boys to look. Crumpled parchment and chocolate frog wrappers littered the floor and half-open trunks sat at odd positions as if creating an obstacle course along the floor. Empty cardboard cases once full of butterbeer were stacked by the door, and a highly suspicious-looking clump of fur and maybe other substances that Ariadne did not want to think about sat at her feet. The state of each four-poster bed made it obvious to whom it belonged. The bed nearest the door was tidily made up with a neat stack of books and parchment on the bedside table. Lupin, of course, thought Ariadne. The next bed seemed to be the epicenter of the candy wrappers and shredded parchment explosion. Pettigrew, she thought with a grimace. The third bed was coated in Quidditch gear, broomstick supplies and red-and-gold Gryffindor regalia. Potter. And then there was the farthest bed, the one Sirius was leading her to now.
"Don't mince words, do you, Morrigan?" he said while rummaging through his own trunk, a black leather thing, strangely, she noticed, embossed with silver and green.
"I don't see the point."
She folded her arms unthinkingly over her chest, covering some of what was exposed when she had unbuttoned her blouse. She thought she caught Sirius glancing at her from the corner of her eye, but he quickly resumed his search.
Sirius' portion of the room was mostly decorated with posters of Muggle women in bikinis hanging suggestively over motorcycles or lounging on beaches. She only knew they were Muggle because most of them did not move, with the exception of one woman in a red dress who was winking at her coyly. But on the bedside table, he also had a stunning astronomical model of the solar system encased in a glass globe, with each planet and moon a twinkling crystal in the black void.
"Beautiful," Ariadne murmured.
Sirius caught her looking at the model and said briefly, "A gift from my cousin Andromeda. Want a drink?"
Ariadne stared at him and the glass of amber liquid he proffered in disbelief. "There isn't enough alcohol for you downstairs?"
"This is mulled mead. Too expensive to buy for the commoners. It's my private stash." He shrugged and drained the glass himself.
"Can you show me whatever this important thing is so I can get out of here, Black? The seventh-year boys dormitory isn't exactly my preferred place to spend my night."
"How can you say that when you've only just gotten here?" he asked in mock indignation.
"I've been here before."
Sirius raised his eyebrows at her.
"To confiscate contraband."
"Naturally."
Ariadne caught the implication in his tone and didn't like it.
"Speaking of contraband," he continued, now holding something behind his back, "remember that part of the deal where you aren't acting as prefect for this one night?"
"No."
"Morrigan, please, work with me here. This…thing I'm about to show you will ensure that McGonagall and Filch aren't coming to end our revelry. Ergo, you will not be on the hook for failing to do your job as a prefect and shutting down the party. Ergo, you should not confiscate the object I'm about to show you."
"Black, the last time I promised you something, it was to come to this stupid party, and that's not going so well. So you'll forgive me if I hesitate to make any more promises."
"Well, if you can't swear to me that you won't turn this in to a Hogwarts professor, then I can't explain to you how I know where every single one of them is, right now."
"You're bluffing."
"Am I? I told you that Filch and McGonagall aren't coming anywhere near our little gathering. If I lied to you about that and they did show up, wouldn't that make me look rather bad?"
"You don't have much a reputation with me to save, Black."
"Ah, right, 'borderline alcoholic and wild parties.' Let me show you something else that I'm capable of doing. Give me a chance to change your mind." He paused. "Besides, it might be a useful little Charms lesson for you. If you're at all interested in magical geography and tracking enchantments."
He really did know the way into her head. Ariadne couldn't deny that she was intrigued. Any object capable of tracking the precise locations of a dozen Hogwarts professors in real time would involve advanced magic indeed. And a lot of rule-breaking.
"Last call, Morrigan," he said, waving a blank, ragged piece of parchment in front of her tauntingly.
"All right," said Ariadne, thinking quickly and learning from his games. "I won't report this definitely illicit and possibly illegal…object," she answered, "if you agree to do all of the theory reading in the next two weeks."
Sirius seemed a little peeved to find his own bargaining scheme used against him. "I've already told you, Morrigan, the theory is useless. I can get us top marks on this project without reading anything. Just leave it to me."
"Unless you can learn to transfigure McGonagall into a hibernating mooncalf that isn't inordinately obsessed with theory, I highly doubt that."
"Look, I don't even have to show you this or tell you anything about it. I'm doing you a favor, love. You can't bargain on that."
"Well, I suppose you'll never get to explain to me how those advanced tracking enchantments work," said Ariadne, shrugging.
The silence of their stalemate hung in the air between them, broken only by the sound of shrieks and thrumming music from the party below. Ariadne was wagering on Black's ego being too big to resist the chance to magic-splain something to her and show off his prowess. What could be more satisfying to him than to impress her, his only real rival in magical skill, with a powerful enchanted object he had created?
"I guess we're done here, then," Ariadne said, turning and making to leave.
"Wait," interrupted Sirius. Ariadne smiled to herself. Men were so predictable. "Fine. I'll do the reading. But swear to me you won't tell anyone about this."
"I promise."
Sirius looked like he needed another drink. Finally, he pulled out his wand, tapped the scrap of parchment, and said, "I solemnly swear I am up to no good."
The parchment unfolded and transformed. Pencil-thin ink lines intricately crisscrossed every surface. When it was finally complete, Ariadne had to hold back her gasp.
It was a perfect map of the castle she knew so well, as well as every person who lived in it. She watched the tiny dot labeled "James Potter" flit erratically around the common room and a lone Slytherin creep around the dungeons. Sirius indicated McGonagall and Filch's offices and living quarters. Based on their still, unmoving dots, it appeared that both were fast asleep.
"How did you compile so many enchantments into a single object?" asked Ariadne, completely engrossed in the map.
"It's not ordinary parchment. It was enchanted already to be able to contain memory, to hold multiple layers of spells. Potter scammed it off some bloke at the Hog's Head. Then Remus and I encoded the spell that would allow the tracking to update constantly, even when the map is not in use."
"Does it automatically pick up new magical signatures—adapt when new people enter Hogwarts?"
"Aye."
Ariadne couldn't deny that she was impressed. "If only you put this much effort into your classes, Black, you could really turn out to be something."
"Can't give a straight compliment, can you, Morrigan?"
"You're missing the secret compartment behind the portrait of Pliny the Older in the corridor leading to the Potions classroom. Slytherins like to hide cursed objects in there."
Sirius frowned and stared at the map. Ariadne watched his deep, dark eyes below brows furrowed in concentration, his mind working, trying to fix the problem. She looked away before he could catch her staring.
"Anyway, Morrigan, there's your proof. McGonagall and Filch are dreaming sweet dreams. Or whatever horrible atrocity Filch probably dreams about. You have nothing to worry about."
Ariadne fished in her bra for a small, milky white crystal glowing dully in the dim room. "My sensors seem to corroborate that."
"Sensors?"
"Sensing charms set around the portrait hole. They detect if anyone other than a Gryffindor student is approaching the common room. Perhaps not as elegant and precise as your system. But they would have alerted me if McGonagall and Filch were in close proximity."
"Does McGonagall know about this?"
"Not exactly. But even if she asked, they're a security measure. It helps me keep Gryffindors safe."
Sirius' eyes glimmered in the darkened room. "What else do you have hiding in there, Morrigan?"
Ariadne held his gaze until they were interrupted by laughter and noises on the staircase. A giggly and intoxicated Priya entered the dormitory, hanging on the arm of a flushed Lupin. They both stopped in surprise when they saw Ariadne and Sirius, heads together, leaning on Sirius' bed.
"Oooh, sorry! Are we…interrupting?" said Priya.
Ariadne practically jumped away from Sirius as though she'd received an electric shock. Sirius hastily began folding up the map.
"No, we were just…leaving," replied Ariadne, trying her hardest not to appear flustered.
"Oookay," trilled Priya, watching Ariadne with undisguised fascination and glee. Ariadne straightened her clothes and made for the door until she was stopped by a low voice.
"Morrigan…we might have a problem."
Sirius was looking down at the Marauder's Map, where a tiny dot of a Ravenclaw was banging on the door of McGonagall's office. Ariadne slowly pulled the sensor crystal out from her blouse. It was glowing red.