The weather was growing colder, and Rose found herself growing more irate. She had never been fond of winter, which was rapidly approaching, and she hadn't even begun to recover from seeing her son, godson, and nephew almost wiped out by a troll. On top of all this, memories of her old school days had been resurfacing with more and more frequency, which always left her with a heaviness in her stomach, as though she had swallowed a rock.

And so, she had withdrawn into herself a little, though not enough to draw concern. She sought private places to spend her free time, away from the prying eyes of students. It was for this reason that on one particular chilly evening, she had sequestered herself in an armchair in the quietest corner of staff room with a new Healing study on the correct preparation of Wolfsbane Potion to achieve maximum effectiveness. She was having a rather good time, all things considered. That is, until she was interrupted by the last person she ever wanted to see.

"Prewett."

She didn't need to look up at the man limping towards her to recognise the voice.

"Sorry Snape, not right now, I'm busy sticking needles in my eyes."

Without hesitation, the Potions Master reached forward and ripped the study from her hands, discarding it on the table next to her. Rose stared at the empty space where the study had been, repressing the urge to slap him around the face.

"Well, that was rather uncouth."

"I need your help."

It was this that got Rose to finally look at him, out of sheer disbelief. His face was drawn and pinched. "Excuse me?"

He didn't say anything in response, but instead flicked his dark black robes aside to reveal a bare leg. Despite herself, Rose blushed and looked away. After years as a Healer, she was used to seeing people in various states of undress, but there was something particularly uncomfortable about seeing below the cloak that Snape used as a barricade between himself and the world.

Snape sneered. "What are you, a child? Look!"

With reticence, she lowered her gaze to his exposed shin. There were several deep gashes and a lot of blood. Rose blinked. "Is that a – dog bite?"

"Never mind what it is," he snarled, brushing a lock of black hair away from his eyes in annoyance. "Can you fix it?"

Rose eyed him warily for a moment, and then shrugged. She picked her study back up and began flicking through it, trying to find her page. "Can't help if I don't know what it is."

If looks could kill, Rose would have been dead on the spot. Nevertheless, she knew it would work. Snape needed her more than she needed him – and he knew it too.

"Fine. It's a dog bite."

She narrowed her eyes. "What kind of dog?"

They glared at each other for a few moments, but Rose did not back down. The pain must have been getting to him, because Snape broke alarmingly fast.

"A three-headed one."

It was enough to pique her interest. With a flick of her hand, she summoned some Murtlap essence from the Hospital Wing, which came whizzing through the staff room window that opened at just the right moment. Then she patted her knee. "Explain."

Reluctantly and with great difficulty, Snape eased himself into a chair and rested his leg on Rose's knee. He watched with a bitter expression as she reached into her pocket to retrieve her dragon-hide gloves. "You can't do this the easy way?"

"No," she said in a condescending way, "I only do that for people I like."

She took his shin in her covered hand, careful not to grip too hard, but firm enough that he couldn't wriggle away. Then with a gentle touch – as much as she would have liked to make it sting a little – she began dropping some Murtlap essence into the wound. Snape's face instantly relaxed and he leant back into his chair despite himself. Rose used the opportunity of his distraction to begin gently dragging her finger against the jagged scars, sewing the skin back together one by one. Snape didn't open his eyes.

"So where exactly did you run into a Cerberus in the castle? Were you out drinking with Hagrid?"

From the expression Snape pulled, Rose could infer that the Potion Master's relationship with the Groundskeeper had not improved since their time as students. "Do you think the headmaster was going to let just anyone wonder into the third floor?"

Rose stopped in her tracks, shooting him a sharp look. "And what exactly were you doing on the third floor?"

He rolled his eyes. "Stealing the Philosopher's Stone, obviously. That's why I came here – to confess."

He had a point. She felt stupid for assuming otherwise.

"Then what were you doing?"

"Protecting it from someone less principled than me."

She hoped he might elaborate, but he didn't. She scrutinised his face for a moment, but the dark eyes gave nothing away. She sighed.

"Fine, have it your way. But you had better hope that Dumbledore backs up your story when I tell him what I saw."

"He sent me, so I assume he will." There was only one scar left now, but it was a big one, and the Murtlap essence was beginning to wear off. The tip of her glove brushed the edge of the gash, and Snape flinched. "Blasted thing. How are you supposed to keep your eye on all three heads at once?"

Suddenly, the door creaked on its hinges, and the two adults snapped their heads around – only to see the very white face of Harry Potter looking back at them. Snape's face screwed up in rage.

"POTTER!"

He ripped his leg from Rose's hands and stood unsteadily. Rose jumped and knocked the Murtlap essence to the ground, sending shards of glass everywhere. She cursed under her breath and waved a quick hand to clear it up.

Harry was backing away slowly from the terrifying figure that Snape was presenting. "I just wondered if I could have my book back."

"GET OUT! OUT!"

"Snape!" Rose hissed, but it was too late. Harry had scampered away, and Snape limped forward to slam the door shut. The remaining cut oozed slightly, a small trickle of deep red. He looked half mad.

"Now what was that about!" Rose said loudly, standing up so that she drag Snape back to the chair. "Sit down, I need to finish."

"He's just like his father!" Snape fumed, as though he hadn't heard a word that Rose had said. "Sticking his nose in where it doesn't belong –"

She couldn't help it – she poked the cut harder than necessary, causing the Potions Master to suck air through his teeth and fall back into the chair.

"Don't speak ill of James in front of me," she said in a low voice as she closed the final wound with a quick stroke of her finger. When she put his leg down roughly, she discovered that her hands were shaking. She looked back at Snape's face, expecting to see fury. Instead, she saw that the shutters had lowered behind his eyes again.

"Funny. I wouldn't have thought the woman who helped enable his murder would care."

Rose blinked, but was so stunned she couldn't say anything. Whatever truce they had brokered to fix his leg had ended. Without even a thank you, he stormed out of the room.

Robin had always considered himself to be a very good chess player. He had always beaten all the boys at Beauxbatons, even the ones that were a lot older than him. However, he had never played Ron Weasley before.

"Rats," he muttered, as Ron's Bishop bashed his Queen around the head with his staff. Ron just grinned.

"Now you have to resign."

Robin ground his teeth, but held out his hand in defeat. Ron gleefully shook it. They had been getting along a lot better since the troll incident, now that Ron and Hermione had stopped sniping at each other all the time. They were a happy little group of four friends now, sometimes five when Neville was brave enough to come and engage in a group conversation. Even when he wasn't, he and Robin found time to hang out just the two of them, eating chocolate frogs and talking about lessons. All in all, Robin was feeling very settled at Hogwarts, finally.

Unfortunately, something was about to happen that would put a spanner in the works. Harry came skittering though the porthole to the common room, struggling to catch his breath.

"Did you get it?" said Ron idly, before he looked at Harry properly. "What's the matter?"

Harry beckoned Hermione closer to them from her seat next to the fire, so that he didn't have to shout. The four of them sat in a huddle, as Harry explained what he had seen.

"I went to get the book back, and I knocked on the door – but no one answered. So I pushed on the door, and I saw Snape. His leg was all ripped up, and Robin – your mum – she was fixing it. And then he said, 'How are you supposed to keep your eye on three heads at once'."

Hermione let out a gasp, and Ron shushed her immediately. "Let him finish!"

"So anyway," said Harry, as though nothing had happened. "I tried to shut the door, and he heard and screamed at me – like really screamed!" He paused dramatically. "You know what this means?"

Robin blinked. "That Snape has anger issues?"

Harry ignored him. "Snape tried to get past that three-headed dog at Hallowe'en! That's where he was going when we saw him – he's after whatever it's guarding! And I'd bet my broomstick he let that troll in, to create a diversion!"

"No, he wouldn't!" Hermione said quickly, shooting a worried look at Robin. "I know he's not very nice, but he wouldn't try and steal something that Dumbledore was keeping safe."

"Honestly, Hermione, you think all teachers are saints or something," snapped Ron, to whom this idea seemed to personally affront. "I'm with Harry. I wouldn't put anything past Snape. But what's he after? What's that dog guarding? And what –"

He stopped in his tracks, his cheeks flushing, and he sent an embarrassed look at his cousin. But it was too late. Everyone understood what he meant. Only Robin was brave enough to vocalise it, however.

"And what's my mum doing helping him?"

"And the Quaffle is taken immediately by Angelina Johnson of Gryffindor – what an excellent chaser that girl is, and rather attractive, too –"

Rose could hear the commentary as she scrambled up the stairs to the staff box. She was desperate to see Harry play in his first game, but a child had broken their arm slipping on one of the stone staircases that morning, and she had been delayed getting there. Even though she had never been enthralled by Quidditch as a sport, she had been surrounded her whole life by people who were. She had seen every game James had played during their friendship, and she wasn't about to miss Harry's now.

She reached the top of the staircase and emerged into the open air of the box, which whipped tendrils of her red hair around her face. All of the staff had turned out for the first game of the year, and so almost every seat was taken. However, there did happen to be one right on the front row, right next to –

"Unbelievable!" she muttered under her breath. But there was nothing for it – the only seat left was next to Snape. Cursing under her breath, she slipped a little more aggressively past Professor Burbage that was necessary in her frustration, causing a line of titters to follow her to the front row.

"GRYFFINDOR SCORE!"

Robin cheered along with the rest of his house, though the cheer died in his throat when he caught sight of his mother sliding up next to Professor Snape in the staff box. They exchanged a few words, though it was impossible to make out what they were from such a distance. He tugged on Neville's sleeve, who was next to him.

"Do you see that?"

Neville followed Robin's finger to the staff box and frowned. "It doesn't mean anything – maybe that was the only place she could sit?"

Robin was not convinced. He had found Neville in the dormitory the night before and explained everything that Harry had told him, but Neville was not as worried as the others. He wouldn't accept that Madam Prewett, who had been nothing but kind to him, could be in league with the teacher who gave him nightmares. In his heart, Robin didn't believe it either, but he was finding it harder to ignore all of the evidence.

"Slytherin in possession…"

Snape would not look her in the eye, but through the corner of his mouth, he hissed, "If you have so much as breathed word of what happened the other night –"

"Keep your hair on," she said through gritted teeth as she smiled and waved at Hagrid, who was, for some reason, sat in the Gryffindor box next to Robin. The groundskeeper waved back at her, though she briefly registered that Robin did not. Strange. "Even though I do firmly believe that you are scum of the earth, I trust Dumbledore's judgement."

He shot her a withering look. "I can't say I feel the same."

Rose was about to say something equally derisive in response, but before she could, a cry of outrage went up in the Gryffindor stands. Her eyes immediately began to scan for Harry, and locked onto him quickly. He was bent over double, not far away from a very smug-looking Slytherin beater. Her heart dropped.

"What a bastard," she hissed at the beater, house pride forgotten. Snape raised an eyebrow.

"Now, now, that's not how we encourage professors to talk about their students."

The Potion Master's self-satisfied smile made Rose's skin scrawl. She had to resist the urge to quickly push him off the edge of the staff box while no one was looking. She consoled herself instead by imagining that Snape had been hit in the stomach by a bludger, in place of Harry.

"So – after that obvious and disgusting bit of cheating –"

"Jordan!"

"I mean, after that open and revolting foul –"

"Jordan, I'm warning you –"

Everyone around him, even Neville, had their eyes glued to Gryffindor's star chasers as they took on the penalty shot, but Robin had not looked away from Harry. He had brought some binoculars to the game, well aware from his time watching the Beauxbatons boys play that it was the only way you could keep track of Quidditch. When Harry had got hit, he had turned them straight to his friend. However, when everyone else turned away, he had kept watching, a nervous sensation making the hairs on the back of his neck stand up. Nothing had happened yet – but he couldn't shake the feeling it was about to…

There it was!

Harry's broom jolted suddenly and shot up several feet in the air. Just as it seemed he had regained control of it, it happened again, and it looked like his grip was beginning to slip.

"Guys," said Robin worriedly, "look at Harry!"

The group turned their gaze to him and Hagrid tutted. "Don't know what he thinks he's doing. If I didn' know better, I'd say he'd lost control of his broom… but he can't have…"

Harry jolted again and Robin winced. "I think he has Hagrid!"

They all gasped as Harry was bucked off of the broom and was forced to dangle off of it, holding on with just one hand.

"Did something happen when Flint blocked him?" came Seamus' voice from behind them. Robin thought this a reasonable thing to suggest, but Hagrid shot him down straight away.

"Can't have. Can't nothing interfere with a broomstick except powerful Dark Magic – no kid could do that to a Nimbus Two Thousand."

Suddenly Hermione reached over and ripped Robin's binoculars out of his hands.

"Hey!" he protested, but she was already scanning the crowds, searching for something. Robin tried to follow the movement of the binoculars with his eyes, but it was impossible.

"What are you doing?" Ron said fretfully, but she did not reply.

After a few seconds, she grabbed Robin's arm in a pincer like grip. "I knew it!" she muttered and thrust the binoculars back to him. "Snape – look."

He did look – and what he saw sent shivers down his spine. Across the pitch from them in the staff box, there was Snape, muttering under his breath – and next to him, her had clasped tightly to his elbow, was Robin's mother.

Hermione was speaking, but he barely heard her. "They're doing something – jinxing the broom."

Robin didn't even bother to defend his mother – the evidence seemed overwhelming now. He felt sick at the thought that she could be trying to murder Harry in that very moment. He had thought that she had wanted to protect him! Whatever that dog was guarding must have been incredibly valuable for her to turn into such a monster.

"What should we do?" Ron whimpered.

"Leave it to me," Hermione said firmly, leaving the boys to look fearfully at Harry, still hundreds of feet in the air.

Rose and Snape, meanwhile, were having a very different conversation in the staff box, though no less fraught.

"Oh, do something Sev!" she whispered, her eyes filling with tears. She was so distraught that she had referred to him by an old nickname by accident, a habit she had fallen out of almost twenty years ago. "Quickly, he's going to fall!"

If Snape had not been so busy muttering a counter curse under his breath, he might have pointed out that he was already doing something, and that her hanging off of his arm and pleading was not in the slightest bit helpful. He had no intention of letting Lily's only son die that day, anymore than Rose Prewett did. And so, he kept a steely-eyed focus on the boy, determined that nothing should distract him.

A few seats behind them, Quirrell tripped, perhaps over his own coat, and fell into their row. Snape didn't even turn around – but all of a sudden, Harry had regained control of his broom and was beginning to scramble back onto it. Snape snapped around to glare at the Defence Against the Dark Arts professor. He had proof, finally, that it was Quirrell who was after the stone!

However, he didn't get to think on this too long, because at that moment, a cry went out next to him. He turned to around, expecting to see Rose looking relieved. Instead, he saw her trapped in a dress that was engulfed by flames.

"It's all my fault," Hermione moaned as she paced back and forth in Hagrid's kitchen. After Snape had managed to extinguish the fire that had torn through Madam Prewett's thin, crinoline undercoats, he and half the staff had rushed her straight to the Hospital Wing. It had taken the students in the crowd a few moments to notice something was wrong, however, as Harry Potter had simultaneously caught the snitch and won the game for Gryffindor. In all the confusion, Hermione had managed to flee the scene of the crime and hide herself in the throngs of celebrating Gryffindor students. She had only just found Robin and explained to him in hushed, shame-faced whispers what she had done, when McGonagall had pulled him aside and given him the story from the staff point of view.

"It's alright, Hermione," Robin said glumly as he lay, face down, on the corner of Hagrid's huge bed. "You couldn't have known that would happen."

"I don't know," said Ron quietly. "Fire does tend to burn things."

Harry kicked him under the table as Hermione pulled fretfully at her hair. "I was aiming for Snape's cloak! I didn't even know that those flames could burn things, or that your mum was wearing crinoline, if I had I would never have –"

"It's alright, pet," said Hagrid gently, although he too looked a little unsettled. "Professor Snape put her out so fast, she didn't even burn! Just quite shocked, I imagine."

Hermione sunk into a chair at the table and sobbed. "I'm going to be expelled!"

"Not you're not!" said Harry fiercely. "Only the people in this room know what actually happened – everyone else just thinks her skirt caught a stray spark. No one here is going to dob you in." He glared around the room. "Are they?"

Everyone turned to Hagrid, who awkwardly tugged on his beard. Eventually he sighed and said, "No, we're not. Honest mistake, I say. But let this be a lesson that meddlin' is not a good idea, even when you think you're right."

"We don't think we're right, Hagrid," Robin said thickly into the duvet. "We know we're right. Harry's broom stopped malfunctioning as soon as Snape was distracted by mum. It has to have been them."

"Rubbish. Why would your mum and Snape do something like that? They don' even like each other!" Hagrid clasped a hand over his mouth. "I shouldn't o' said that."

"Yeah, well, they seemed pretty close this morning," muttered Robin, remembering his mother's hand on the Potion Master's elbow.

Then something occurred to him that made him want to throw up. Snape couldn't – he couldn't be – could he?

But then his mind began thinking rationally again. Snape couldn't be his father. He also had dark eyes, darker than his mother's, and he didn't have any similar features to Robin. He was also a Slytherin, which goes against what his mother had told him.

Although maybe she was lying? She wasn't exactly looking like a very trustworthy source these days.

"I found something out about them," Harry said to Hagrid, oblivious of Robin's inner turmoil. "He tried to get past that three-headed dog on Hallowe'en. It bit him, and then Madam Prewett helped him cover it up by healing his leg. We think they're trying to steal whatever its guarding."

Robin was expecting Hagrid to jump to his mother's defence – somewhat hoping he would. However, the groundskeeper instead dropped the teapot he was holding, sending shards of china around the room.

"How do you know about Fluffy?"

"Fluffy?" the children chorused in disbelief. It was enough to make Robin sit up on the bed.

"Yeah – he's mine – bought him off a Greek chappie I met in the pub las' year – I leant him to Dumbledore to guard the –"

"Yes?" Harry said quickly. Hagrid frowned.

"Now don't ask me any more. That's top secret, that is."

"But Snape and Madam Prewett are trying to steal it!"

Hagrid shook his head angrily, and said again, "Rubbish! Snape's a Hogwarts teacher, he'd do nothin' of the sort. And Robin – if I were you, I'd be ashamed to say such a thing about me own mum. Especially after all that she's been through!"

Robin blushed. In his heart, he too couldn't quite believe it about his mother, who had never been anything but kind, despite her rough exterior. He opened his mouth to ask Hagrid what he meant by 'all she's been through', but Hermione cut him off.

"So why did they just try and kill Harry? I know a jinx when I see one, Hagrid, I've read all about them! You've got to keep eye contact, and Snape wasn't blinking at all, I saw him!"

But Hagrid wasn't having it. "I'm tellin' yeh, yer wrong! I don' know why Harry's broom acted like that, but Snape wouldn' try an' kill a student. Neither would Madam Prewett for that matter, especially not her! Now, listen to me, all three of yeh – yer meddlin' in things that don' concern yeh. It's dangerous, and you almost did serious 'arm to Madam Prewett today, which I know you'd never have forgiven yerselves for. You forget that dog, an' you forget what it's guardin'. That's between Professor Dumbledore an' Nicholas Flamel –"

"Aha!" said Harry triumphantly. "So there's someone called Nicholas Flamel involved, is there?"

Hagrid buried his head in his hands.