Draco hadn't recognized Sirius Black at first, and was shocked at how different he looked now; when he had first met the man, Azkaban had taken its toll on him, just as it had on his Aunt Bellatrix, leaving Sirius gaunt and wraith-like. Even before the summer, when he had showed up at the Department of Mysteries, his appearance was ragtag, his aristocratic features hidden behind overgrown and messy hair; his face was unshaven, and the clothes he wore were old and dirty. But thinking on when he had seen him last, Draco remembered that Sirius had been unconscious – for weeks. He wondered if even Harry or the others knew he was in fact, awake, well, and one of Hogwarts newest teachers; he wondered how long Remus and the rest of the Order had been lying to them. Even though Sirius had yet to really begin their lesson, Draco moved to raise his hand (feeling rather like Hermione must) – he felt that he and his friends had been slighted; they had worried over Sirius the whole summer, after all – but was surprised to find his body unresponsively immobile. Up at the front of the room, Sirius smiled at Draco, his expression telling him that now was neither the time nor the place to discuss the things he wanted to ask. The new professor turned, and Draco saw only then, that his wand was held lithely in his hand, barely noticeable, but he had not seen so much as a flick to enact the spell he'd cast on Draco.
"First lesson in Defense against anything is to expect everything – consider everything, and in order to do that, you must know everything." His eyes were still on Draco, and the smile on his face twisted slightly as if he were really enjoying the younger man's discomfort at learning the lesson first hand – even if it was just between the two of them.
"That's a bit unreasonable, isn't it?" Blaise remarked irritably. "There's no way we can know everything. Even in a familiar situation, there are too many unpredictable variables."
Sirius now turned his attention to Blaise, and studied him a moment before replying. "You should pay closer attention to your surroundings, Zabini. Do you think your mother managed all those marriages because she didn't know everything there was to know in order to make them happen?" Draco had never seen his friend so angry, but Blaise could say nothing in return. "Besides, all variables – even the most seemingly unpredictable – follow a pattern. You just have to know how to read them. Nature has rules, and people are creatures of habit." Sirius pulled a piece of parchment from one of the books he'd thrown onto his desk and looked it over. "Slytherins," he muttered to himself with a cynical look.
"Professor…"
"Black," Sirius finished for the student without looking up. "Sirius Black, for those of you who haven't figured it out yet."
Judging from the change in expression on some of the other student's faces, it was obvious some of them hadn't realized who their new professor was until that moment. With quick glances here and there, Draco tried to guess what the others might be thinking: Sirius Black had been, before the summer, still on the run – a wanted man, but Professor Dumbledore had since vouched for him and all the charges against him dropped. "And," he continued, his gray-eyes twinkling mischievously. "If you don't want to call me 'professor', you may address me as 'Lord Black' – because when it comes to blood purity, mine is still richer than any of yours."
"It counts for naught if you're a blood traitor," Daphne Greengrass argued with disgust.
At first, Sirius did not respond, but he regarded the student without bothering to mask his disdain, which seemed far greater than the contempt she had for him. Perhaps it was his good looks, or the fact that he was older, or maybe it was simply the superiority his presence exuded over her, but Daphne quickly dropped her stare. "If you don't want to take the class, you're welcome to leave. That goes for any other student," Sirius said plainly. "But as I will be teaching you to fight for your life, and the lives of your loved ones – and, conversely… well, Dumbledore doesn't want me to use the word "kill", so we'll go with: how to give your enemy a run for theirs – you'd better be bloody sure before you walk out that door, because there will be no getting back in."
The class grew uncomfortably quiet, and even Daphne, who sat scowling at the surface of her desk, didn't dare move. After the silence had become sufficiently awkward (Sirius making no attempt to break the tension), Theodore raised his hand. "Professor Black," he began, his tone as plain as Sirius's had been. "Does the Headmaster not have any reservations in teaching us Slytherins the same curriculum as the rest of the school – considering our increased proclivity to the Dark Arts and Pure Blood Elitism?"
"You already know well that the Headmaster intends to treat every student equally. He's a good man, like that. The way I see it, however, is that, it's not much fun, if the other side doesn't at least put up a fight." In a sudden change of pace, Sirius flipped his wand up, catching it in his hand at the ready. "Alright, enough talk," he said, a smile once again on his face. "Let's see what you kids can do."
It was simple: each student would face off against Sirius, the goal, to turn the other person's hair a bright, neon green. The students were allowed a total of three additional spells to aid them in this task, while Sirius was only allowed the one. While the order appeared random at first, it became clear about halfway through to Draco that this was also part of the test; Sirius wanted to see what each successive student would learn from the previous. Theodore was the last to go, which was a clear indication that Sirius considered him to be the most talented among them. Theodore was one of the few Slytherins who had mastered wordless spells, giving him that advantage – though, as a now green-haired Draco had proven before him, it was not nearly enough to best their professor. Sirius waited patiently as Theodore removed his robe, handing it to Gregory who stood off to the side with his other green-haired classmates.
The student took a moment before raising his wand. He was almost as tall as Sirius, though much thinner, and there was an awkwardness about him that he would likely never grow out of. But despite his youthful appearance, there was a determination in Theodore's eyes that even their professor seemed to take seriously. Most noticeable though, was the air about the classroom as Theodore got ready to go head-to-head with Sirius: all the other students were behind him; even without words, their encouragement was evident in their body language; it was written on their faces. The Slytherins were unified.
Unlike a formal duel, there was no bowing to your opponent. As soon as Theodore was ready, he was allowed to cast his first spell, but he turned his wand not toward Sirius, but rather, on himself.
"Ha!" Sirius laughed, zinging the colour charm at Theodore and effectively interrupting his attempted Disillusionment Charm. "Good idea, Nott, but I won't give you the chance." Probably suspecting as much, Theodore retaliated with a rebounding shield charm where he could direct the trajectory of the repelled spell. This forced Sirius to dodge with a chuckle, though he fired several more spells at Theodore, controlling his path of movement. Now he was steps away from the corner of the classroom, with no where to run. The Slytherin student's eyes traced the room, taking in the position of every object and student within its walls; he cast the colour charm hoping to make a breakaway but Sirius merely ducked around them, charging forward. Using a levitation spell, Theodore launched a desk at Sirius – but now he only had one additional spell left. Turning quickly, Theodore pointed his wand at Blaise and shouted, "Imperio!" Blaise's eyes became unfocused but his body jumped into action, gripping his wand and running forward to join the fight.
For the first time since the activity had begun, Sirius looked impressed, though in a dark way. Blaise's hair had already been turned neon green, so it didn't matter that Sirius's spells hit him. It seemed like Theodore might actually win, casting a variety of spells through Blaise (and thus, staying within the parameters of the test), when Sirius physically kicked a desk into Blaise's path, causing Theodore to have to change his friend's course or risk injury. But the distraction was all Sirius needed to rush forward and knock Theodore's wand out of his hand; it clattered across the floor far out of reach. "Takes a bit of practice, that Imperius Curse," he remarked smugly. "Beginners lack a fluidity between their own actions and the actions of those they're controlling. But that was a gutsy move," he added with an approving nod. Draco had a sense that Sirius was praising Theodore for prioritizing his friend's safety above personal victory, rather than his use of the Imperius Curse. The smirk on Sirius's face widened and he pointed his wand at Theodore. "Crinus Muto Verde."
The Slytherins would learn shortly after class that Sirius had not been entirely truthful about the nature of their test: Not only had he turned their hair neon green, but he had woven in a spell of secrecy that prevented them from divulging any information about the class; anytime anyone tried to share anything about their Defense Against the Dark Arts lesson, they would break out into a verse of some Muggle song. And, if there were more than one of them together, the spell would cause them to automatically harmonize.
As the Slytherins exited the classroom, the waiting sixth-year Gryffindors burst into laughter; even Hermione was in tears to see Draco and the others with acid green hair.
"Dunno who's teaching, but I like 'em already!" Ron guffawed, doubling over.
"Just you wait, Weasley," Blaise remarked, elbowing past him roughly.
"Oh come now," Hermione soothed, trying to hold back her laughter. But Draco glowered still, even as she brushed a hand through his hair. "We're not making fun of you, but it's funny."
"You won't think it's so funny when –" Draco looked back into the classroom and was surprised to see that it was empty; Sirius had disappeared. "Hey," he exclaimed, half-turning on the spot. "Where did –" but the remainder of his sentence was replaced by song, and with the rest of the Slytherins in close proximity, it was like an impromptu performance that brought every student passing through the corridor to their knees in laughter.
By lunchtime, the hallways of the castle were noticeably more colourful as students of varying years and houses walked about with vibrant hair in the most unnatural of hues. Some didn't seem to mind as much as others; Draco had met Luna on the stairs, her usual long blonde hair now a vibrant blue. She seemed to rather enjoy the change though, having conjured herself a headband of dangling silver stars to match. But Draco's greatest consolation came after lunch, when the Slytherins were reunited with the Gryffindors for Potions, and he watched with vindictive pleasure as every single one of them filed into the dungeon with vivid magenta hair. Ron had made the mistake of wanting to harp on their newly appointed Defense Against the Dark Arts professor only to result in the rest of his housemates joining him for a particularly spirited number.
"I thought you two weren't going to take Potions," Draco commented, after the Gryffindors had fallen into an angry silence, glaring at Ron as they set up their cauldrons.
"McGonagall says Slughorn only requires an 'Exceeds Expectations' to continue for N.E.W.T.s," Ron explained, his face still deep crimson from embarrassment (and likely self-loathing). He and Harry, who were sharing a station, were given supplies found in the cupboards of the classroom to use until they could acquire their own equipment, including two rusty cauldrons, and a set of tarnished scales they would have to share. Professor Slughorn loaned them each an old copy of Advanced Potion-Making by Libatius Borage, though the texts appeared older than they were.
Though Professor Slughorn's style of teaching was very different than Professor Snape's, Draco had to admit he still enjoyed the lesson, though without the favour of their former professor, Draco and the other Slytherins had to put a bit more effort into their work. Just as Sirius had given the students a practical challenge, Professor Slughorn presented them the opportunity to win a vial of Felix Felicis – or Liquid Luck; enough for one perfect day. Draco had been expecting Hermione to win, but to his – and everyone else's surprise, it was Harry who claimed the prize.
"How do you suppose Potter won?" Draco asked Theodore as they settled down in the common room during one of their free periods. "I mean, he's never been any good at Potions." Their other friends had continued with classes they had opted out of, thus leaving them some time to start the mountain of homework they had already been assigned. But for once, Theodore didn't seem to be in the mood to do work. He sat back in his chair, watching a small group of seventh years playing a game of cards. When someone walked by, he was jolted from his reverie; he glared at Pansy, who had accidentally dropped a few of her books on her way out. She was alone – though that wasn't unusual these days – and as she met the eyes of the two boys, Draco noticed she tugged obsessively at the sleeves of her robe. After she left, and it was just the two of them again, Draco leaned forward. "Did you see that?" he asked. "The way Pansy was –"
But Theodore interrupted him, looking much more serious than even Draco was feeling. "Draco: I need to tell you something."