Chapter Text
July 1975
Any professor – honestly, any professor you could find at Hogwarts – would have taken one look at the Potions lab that Thursday morning and assumed that they were dreaming. All the fourth-year Slytherins and Gryffindors had paired off together, little pockets of ruby and emerald all across the dungeon. And, rather than the usual hiss of poisonous whispers, insults, and threats, the room hummed with quiet voices and muffled laughter.
“Careful, everyone!” said Slughorn, beaming at the rows of cauldrons and smiling faces. “It’s a light touch that brings out the clarity. Don’t let your personal humours bleed into the batch!”
Naturally, the entire class had failed that all-important light touch part. They had set out to brew a variation of the Draught of Mutual Understanding – a volatile, experimental concoction that was supposed to clear the mind of trivial biases – and the steam rolling from the surface of the carefully concocted potions was so potent that… well, that even the likes of Severus Snape and Sirius Black (paired together by a cruel twist of the alphabet) had found a way to bridge their divides.
The two teenagers were leaning over the same cauldron, stirring the violet mixture and breathing in the thick steam. Sirius felt a strange warmth at the base of his skull, unable to put his finger on why the persistent resentment he usually felt towards the boy on his left had simply… vanished. “You’ve added too much valerian,” he pointed out mildly.
“And you,” Severus replied with a smirk, “have been stirring clockwise for an entire minute. You’re going to turn it into sludge.”
“Really?” Sirius asked doubtfully, looking at the silver spoon in his hand.
“Yes. You’re supposed to add one counter-clockwise for every fifth stir.”
This sounded, Sirius reasoned, far too complex for his brain to navigate right now. “Show me, then.”
Without a hint of his usual malice, Severus reached out – but he didn’t take the proffered spoon. Instead, he wrapped his fingers around Sirius’s and began directing his movements, explaining what he was doing as he did so in his cool voice. Beneath their ministrations, the swirling potion turned a deep indigo. Sirius didn’t notice, however, for he was no longer looking at the cauldron; he was watching the way the other boy stared into its depths with such an intent expression on his face.
“The book doesn’t say anything about the counter-clockwise stir,” Sirius pointed out.
“You can only learn so much about potion-making from books,” replied Severus.
“But how did you know to do it?”
Severus kept his fingers ghosted over Sirius’s knuckles, his attention fixed entirely on the shifting vortex within the cauldron. “I spend more time in the Restricted Section than in the Great Hall or the Quidditch pitch,” he said, his voice unusually steady. “Most people follow the instructions because they’re terrified of failing. I follow the ingredients. If you watch how the valerian reacts to the heat, you don’t need a book to tell you it’s fighting the base. It’s simple observation, Black.” He tilted his head, a stray lock of hair falling over his eyes. “Most people are just too busy looking at their own reflections in the surface of the cauldron to notice what the potion actually wants,” Severus added, his tone softening just a fraction.
Fascinated, Sirius stopped fighting the guiding pressure of Severus’s hand, letting his own wrist go slack. “You make it sound like you’re talking to it,” he said. “I’ve watched you fuss over potions like this for years and I always thought you were just doing it to… be difficult.”
Severus finally glanced up, his dark eyes meeting Sirius’s gaze. Under the influence of the potion’s fumes, there was no defensive wall, no immediate flinch. “I am difficult,” he said, lips twitching at the corners. “But that doesn’t mean I’m not also correct. The two things aren’t mutually exclusive, Black.”
That made Sirius snort. He watched the way Severus’s fingers tightened slightly against his own before loosening, and frowned slightly. “You know,” he said, his gaze flickering down to Severus’s mouth before snapping back to his eyes. They were so dark he could barely see the pupils in them. “It’s actually infuriating. How much time we spend trying to destroy each other when you’re one of the only people in this school who can actually keep up.”
Severus went still. “Is that right?” he asked, thumb distractedly brushing against Sirius’s knuckles. “And what would you rather be doing instead, Black?”
“Making beautiful potions, of course,” said Sirius with a dazzling smile.
The flush was creeping up Severus’s neck. “You’re a monumental idiot, Black. But… I suppose I prefer your idiocy to the general populace’s mediocrity.”
“Is that a compliment?” Sirius asked, leaning a little closer.
“If you prefer to think of it that way.” Severus replied, eyes now tracing the sharp line of Sirius’s jaw. He sighed, the confession leaking out of him without warning. “I spend so much time watching you. It’s exhausting.”
“I know.” Their hands continued the gentle stirring motions, but neither teenager was watching the cauldron to see the effects anymore. “I’ve seen you.”
“Which means you’ve been watching me, too.”
They were inches apart, the rest of the dungeon fading into a blur of meaningless murmurs. The potion’s haze made everything feel frictionless and, across the room, students were laughing, crying, and confessing secrets they’d typically guard with their lives. “You’re staring right now,” Sirius pointed out, leaning so close that Severus could see the green flecks in his grey eyes. “Why are you looking at me like you’ve been starving?”
“Because,” said Severus, “I wanted to know what you look like when my vision isn’t obscured by the daggers in my eyes.”
Sirius nodded, as if that made perfect sense. “And? What’s the verdict, Sev?”
“It’s…” but the sentence trailed off. “It feels like leaning over a precipice.”
Sirius searched Severus’s dark gaze, stripping away the years of vitriol until there was nothing left but aching curiosity. “A precipice,” he muttered, hand turning over in Severus’s fingers. His thumb pressed against the frantic pulsing point in the other boy’s wrist, and he smiled uncertainly. “Well, sometimes it’s better to jump before you fall.”
Severus’s eyes seemed to swallow the light, the dungeon, the entire world. To Sirius, it was as if the looming, suffocating weight of their respective futures had simply ceased to exist. There was only the heat of the cauldron and the terrifying, magnetic pull of the boy he was supposed to loathe.
“I’ve memorised everything about you,” Severus breathed suddenly against his ear, his voice raw with the kind of honesty that only a dying potion could permit. “The way you tilt your head when you’re cornered, the way you laugh when you’re actually angry. The way you smile all the time with your mouth, but you only actually mean it when your eyes crinkle at the edges.”
“You saw all of that with daggers in your eyes?”
“I did.” Severus’s breath was hot on Sirius’s neck now. “I’ve spent a very long time hating you, Sirius Black. I sometimes wonder what might happen if I stopped.”
“Stop, then,” Sirius said daringly. “You might be pleasantly surprised.”
The air between them felt charged with the kind of static that precedes a lightning strike. Severus parted his lips, his gaze dropping to Sirius’s mouth, as his trembling hand hovered at the back of Sirius’s neck. Then, the potion – already taxed by their lack of attention – let out a high-pitched screech as the mixture surged upwards. The indigo turned a sickly sludge-brown. A plume of acrid steam erupted outwards, hitting them both like a physical blow, and the illusion was shattered instantly.
Sirius flinched as if he’d been struck, his hip slamming into the stone workbench. Severus recoiled even faster, his hand flying to his throat as if to check that his skin wasn’t burning. For a heartbeat, they stood there with their chests heaving and eyes wide. Then, the whiplash of Sirius’s own vulnerability turned into primal rage as he shoved Severus back, the force of it sending them both stumbling.
“You had your hands on me, you slimy snake!” Sirius snarled.
“You,” Severus hissed back, eyes darkening, “were the one pulling me in, you pathetic –”
“I was clearly under the influence of that… that filth you created in our cauldron! One stir counter-clockwise?” Sirius let out a hollow laugh, looking sickened. “I’m onto you, Snivellus.”
“You dare blame me for your own weakness?”
“Weakness? Get over yourself. I wouldn’t touch you with a ten-foot pole, you greasy-haired prick!”
Severus lunged, his fingers catching the collar of Sirius’s robes, and they went down in a tangle of limbs. Glass shattered. Vials of lacewing flies and powdered moonstone exploded into a glittering, choking cloud. For a second, it seemed uncertain who would overpower who on the stone floor until Sirius tackled the other boy, pinning his shoulders to the floor, his face a mask of furious humiliation.
The class began jeering and shouting almost automatically. A few rows back, in fact, James Potter – shaking off the haze of his own potion (which had seen him be polite to Macnair, of all the bloody people) let out a bark of laughter. “Go on, Pads! Give him a proper jinxing!”
Peter Pettigrew giggled, leaning over the desk to get a better view. “Look at him go! Snape looks proper terrified.”
Their voices went entirely unheard as Sirius bunched the other boy’s robes in his fists and shook him violently, staring down at Severus with a murderous look – one tinged with something more dangerous: absolute longing.
Then, a strong hand clamped on his shoulder and hauled him back onto his feet.
“Sirius, calm down,” Remus Lupin urged, holding onto his best friend’s shoulder. He had been working pleasantly enough alongside Celestina Warbeck – although, to be fair, he’d never needed a potion to get along with anyone. “Breathe.”
Finally free, Severus scrambled to his feet, dusting off his robes with hands that wouldn’t stop trembling. He ignored the sound of James and Peter’s laughter (he was far too used to it), staring instead at how Remus’s hand was sitting so gently on Sirius’s shoulder. How Sirius, even at his most volatile, leaned into the grounding touch. How Remus knew exactly how to dim the fire in Sirius’s eyes when no one else could. It was an intimacy of years, of shared secrets, of casual, unthinking touch… and completely unlike the violent distance that stretched between himself and the boy with green flecks in his grey eyes.
“Mr Snape! Mr Black!” Slughorn’s voice boomed. “You’ve destroyed half my supply cupboard! Five minutes ago you were brewing like model students, and now you’re acting like… like wild beasts!” And for some reason, James laughed even harder at that, waggling his eyebrows grotesquely at his friends until Remus shook his head at him.
“He started it, sir,” Sirius spat, still shaking.
“I beg to differ, sir,” snarled Severus. “Everyone knows that Black is –”
“I don’t care who started it!” Slughorn roared back at them. The professor looked more furious than they’d ever seen him before, his eyes practically bulging out of his head as he stared at the scattered ingredients and broken glass. He’d only stepped out of the classroom for a minute. “Detention. Tonight.”
Sirius blinked. “But it’s the last day of –”
“Tonight, I said! You will assist Hagrid in his nightly survey of the Forbidden Forest. And if I hear so much as a whisper of a fight, I will ensure neither of you returns in September. Do I make myself clear?”
The two teenagers stood on opposite sides of the room, both of them trembling, both of them trying to scrub the phantom sensation of the other’s touch from their skin.
“Crystal, sir,” Sirius echoed, shooting a final, hateful glare at Severus.
“Yes, professor,” Severus added, his composure hanging by a thread. He turned on his heel, but he didn’t make it two steps before he slipped on a spilled potion and went flying. James let out a mocking wolf whistle, Peter spluttering with laughter beside him. And Lily Evans, who had been watching the scene with growing horror, all but erupted.
“You’re pathetic,” she snarled at the dark-haired boy, and he fell back in his seat as she advanced on him. “Honestly, have you ever considered growing up?”
“Oh, come off it, Evans,” he replied, grin faltering ever so slightly. “It’s just a joke.”
“Then your sense of humour is almost as dire as your bloody Potions grade,” she shot back, pushing through the dispersing crowd to reach Severus. She wasn’t alone, either, for Narcissa Black had already materialised at Severus’s side, stepping into Sirius’s line of sight and effectively blocking his view of her friend.
“You’re behaving disgracefully, cousin,” she said coolly, her voice cutting through the murmurs of the room. “Rolling in the mud like a common brawler? It is beneath you.”
Very red in the face now, Sirius stiffened. “Stay out of it, Cissy.”
Narcissa’s eyes flickered over his shoulder to where Remus stood watching her, an unreadable expression on his face, then shifted back to Sirius. She reached out, adjusting her cousin’s collar for him. “Fix your robes,” she commanded, although her voice had softened. “And stop looking at him as if he’s murdered our entire lineage.”
“Have you met any of the other Blacks?” he countered, trying to summon back some of his usual effortless charm. “I wouldn’t murder him for it; I’d give him a bloody medal. I’d kiss the smirk right off his stupid face.”
That made his cousin’s eyebrow arch ever so slightly. “Even so,” Narcissa said, “you look deranged. Try listening to your friend.” Her eyes flickered back to Remus. “The polite one, I mean, rather than the two sniggering loons over there.”
“Oi!” said James.
Ignoring the buzzing argument around her, not to mention Slughorn’s voice ordering them all to get out of his dungeon and go to their next class, Lily rested her hand on Severus’s sleeve. “Are you alright, Sev?” she whispered.
“Fine,” he replied, fingers coming up to meet hers. “It’d take more than a hotheaded Gryffindor to –”
“Don’t,” she urged. “You have the high ground for a minute. Try not to waste it, yeah?”
Rolling his eyes, Severus looked past her, catching Sirius’s eye one last time. His rival was still being held back by Remus, but the connection was still there – the terrifying knowledge of what they had almost done. Then, Lily tightened her grip on his arm, and Narcissa moved closer, their collective presence creating a wall that pulled him firmly back into his own world.
“Let’s go,” Narcissa said.
Severus let the two girls lead him away, the sound of his boots echoing against the stone, very aware of Sirius’s eyes burning into his back. And he left in his wake the broken glass, the scent of burning valerian, and the silence of a truth that no one else in the room could quite understand.