I taught him! I thought I knew him!

This can be read as a stand-alone fic, but if you read the prequels "Why Snape never eats here", "Malice in his voice", "Threesome at Spinner's End" and "Dumbledore was pretty firm with him" and the sequels "Well done, Draco, well done" and "Power the Dark Lord knows not" you will get a better feel for the particular version of the Potterverse in which this story is set.

Chapter 1: Minerva

Severus has got all the Death Eaters out of the castle, it's not quite clear what happened, she supposes that he must have had to go with them, to keep his cover. But why hadn't he been able to warn them of the attack? She's sure that he hadn't known they were coming, he hadn't known there were Death Eaters in the castle until Filius told him. She wonders – does Voldemort know? Does he know that Severus is a spy? Doesn't he trust Severus any more? But Hagrid has said something about Severus being involved in Albus' death – Harry was there, he told Hagrid – it's very confusing, she needs to speak to Harry directly to sort out what happened. Meanwhile, she's given orders that everyone is to go up to the Hospital Wing, and she's gone to see Albus' body, she won't believe that he's really dead until she's seen the body herself. Even with the evidence of the body it's hard to believe it – Voldemort's Death Eaters have killed the greatest wizard of modern times, but how? Not even Voldemort could do it, though he tried hard enough in the Atrium of the Ministry of Magic. Albus' right hand was getting worse, not better, but even so … how could Voldemort's servants have done what he could not do himself?

She thinks, I've been teaching at Hogwarts for forty years, but I've never wanted this, I've never wanted to be Headmistress, I've always thought Severus would be Headmaster after Albus. One day when Voldemort was gone and Albus was ready to retire, I thought Severus would be Headmaster, the first Slytherin Headmaster since Phineas Nigellus – if the Board of Governors and the Ministry could overlook his past, if they could overlook the Dark Mark branded on his arm.

Then she hears Fawkes singing his lament and she knows that it's true, really knows, in her heart and not just in her head … Albus is dead, at the hand of one of Voldemort's Death Eaters. She thinks, will Albus be remembered only as Voldemort's greatest victim, and not as the mighty wizard who defeated Grindelwald? Oh, Voldemort is truly evil, but compared to Grindelwald, his ambitions are puny – he only wants to be the Minister for Magic, and to terrorise the Muggles a little! Grindelwald's malice against the Muggles was so great, he whipped them up to fight against each other with such violence they might have exterminated each other, she's read Muggle books about their version of the war against Grindelwald, they died at the rate of fifty thousand a day during the six awful years of their war. Muggles may not have magic, but they have horrific ways of killing each other, it took powerful wards to protect a wizard's home during the Blitz. What a pity a Muggle bomb didn't hit Tom Riddle's orphanage …

She remembers Tom Riddle from her own school days, shudders to think that the intelligent, charming, handsome boy she'd once yearned after has turned into the monster Voldemort, but she thinks, even he is not so mad as to believe that all the Muggles can be killed. No, Voldemort isn't mad, he's quite chillingly rational, the Muggles are just pawns in his plan, he lets his Death Eaters kill and torture them for fun but they're not his serious targets, unlike Grindelwald. Oh dear, it's a good thing the Muggles don't know how their world was nearly destroyed by the malevolence of one mad wizard and his followers, and the indifference of the rest …

Harry, Ron and Hermione – even Remus – can have no idea what it was like for her, growing up in the shadow of Grindelwald, growing up during the most terrible flare-up that has ever swept this ball of mud on which we live. And who knows how long the storm would have raged, how horrible it would have become, if Albus hadn't intervened? Even now, there are some in the Ministry who think – thought – him a Muggle-loving old fool. So many wizards pay no attention to Muggle affairs, don't realise how dependent the wizarding world is on the Muggles, good lord there are sixty million Muggles in Britain, and how many wizards? Ten thousand?

The Ministry of Magic had done nothing until Grindelwald's disruption of the Muggle world started to hurt them, until the trickle of refugees from the Continent became a flood, and even then they'd done precious little to help the Muggles. It was Albus who ended the madness, it was Albus who sought out Grindelwald, defeated him, captured him – Albus would never have used an Unforgiveable Curse. How ironic it was that Grindelwald had killed himself in prison rather than face trial, with the Muggle tools of a rope and a chair! And it was Albus who had insisted on opening up a channel of communications between the Ministry and the Muggle Prime Minister of the day … Oh, the Ministry has always taken Voldemort seriously, he's a British Dark wizard who wants to be the Minister for Magic, not a foreigner who only threatens Muggles!

She thinks, Albus, it was nearly sixty years ago but I will never forget what you did for the Muggles, I will never forget what you did in the war against Grindelwald, and with the phoenix's song in her ears she walks into the Hospital Wing to deal with Bill Weasley.

Ron, Ginny, Harry, Hermione, Luna, Nymphadora and Remus are gathered around Bill's bed, "Molly and Arthur are on their way," she says, and they rouse themselves as if from a trance.

She turns to Harry. "Harry, what happened? According to Hagrid you were with Professor Dumbledore when he – when it happened. He says Professor Snape was involved in some …"

Harry replies, "Snape killed Dumbledore," and her world falls apart.

She stares at Harry for a moment, then sways as if she might faint. Poppy conjures a chair and pushes it under her just in time.

"Snape," she repeats weakly, falling into the chair. "We all wondered … but he trusted … always … Snape … I can't believe it …"

Severus killed Albus? But Albus trusted Severus, trusted Severus completely! She remembers when Albus first told her that Severus had been a Death Eater, it was just after the fall of Voldemort, Severus' behaviour had been so odd, most people had celebrated wildly, even those who had been Lily and James' friends – and heaven knows, Severus was no friend of James – but Severus had locked himself in the dungeons and according to the house elves he'd smashed them up rather badly. Eventually Albus had been forced to break the wards and go in and get him out, she doesn't know what passed between them, but Severus has never been quite the same since.

She'd been shocked to learn that there was a Death Eater under the roof of Hogwarts, but not really surprised to hear that Severus Snape had gone to the bad, given who his friends were and his notorious interest in the Dark Arts, it would have been more surprising if he hadn't. But Albus had assured her that Severus had rejoined their side before Voldemort's downfall and turned spy for the Order at great personal risk, and she'd known that Albus had a number of useful sources of information. And Severus had knuckled down and worked hard, sour and sarcastic as he was, he didn't shirk his duties, his students usually did well in their OWLs and NEWTs, and he was an exemplary Head of House, he might favour his Slytherins in public but in private he was strict with them, and nothing happened in the Slytherin common room or dormitories that he didn't know about. So she'd got used to having him around and well, she couldn't say that she actually liked him, but she didn't dislike him and she certainly respected him, he'd been a tower of strength to Albus since the trouble with Quirrell and the Philosopher's Stone.

She thinks, I would have sworn that Severus was devoted to Albus, I know he hated Umbridge as much as I did, he just managed to conceal it better than I could, and I've sat through umpteen years of staff meetings, umpteen years of watching the two of them together, and Severus never hid how much he liked it when Albus would come into the room, stand behind his chair, and put his hand on Severus' shoulder. To tell the truth, it had annoyed her slightly, how he gloated over the attention that Albus gave him, she'd think, a little spitefully, really, Severus, if you had a tail you'd wag it … and Harry's arrival at Hogwarts really put Severus' nose out of joint, the idea was ridiculous but he almost acted as if he were jealous of Albus' affection for the boy. It's unbelievable, impossible, that Severus would raise wand or hand against Albus, but Harry wouldn't lie, it must be true …

"Snape was a highly accomplished Occlumens," Remus says, harshly. "We always knew that."

"But Dumbledore swore he was on our side!" whispers Nymphadora. "I always thought Dumbledore must know something about Snape that we didn't …"

She thinks, Albus wouldn't tell me, he wouldn't tell anyone why he trusted Severus. And Severus – well, he was always difficult, she hadn't envied Horace having Severus in his House, talented boy though he was. She will never forget that ugly incident in the corridor outside her classroom in his first week at Hogwarts, when Severus had disarmed Sirius Black, and Sirius had lost his temper, tried to punch Severus, and Severus had smashed every bone in Sirius' right arm and hand - so badly that Poppy had needed to remove them and re-grow them with Skele-Gro – with a bone-breaking curse that she'd only ever read about herself. Why oh why couldn't he have just scuffled with Sirius, Muggle-style, like any normal boy? His family background was unhappy, and the old scandal involving the Prince family had to be taken into account, but why did Severus have to react to every little provocation so aggressively, why did he have to feud so relentless with the Marauders? And Severus had grown up to be a very wild boy indeed, as wild as Sirius Black, but without Sirius' easy charm, the kind of wild boy that foolish, loving girls like that little Hufflepuff, Florence - what was her name again? – thought that they could tame.

She thinks, and that has been a perennial problem, every year some girl gets a crush on him, some clever sensitive girl who's read too many fatuous Muggle romances and fancies herself playing Jane Eyre to his Mr Rochester, I'd be a little worried about Hermione Granger, I know that she admires his intellect, if it wasn't so clear that she and Ronald Weasley are meant for each other, and Severus has always been so quelling towards her. Yes, Severus can be trusted with the female students, but not with the staff, his behaviour towards every good-looking young female staff member foolish enough to be attracted to him has been abominable, and I don't know what he gets up to on those weekends when he slips away from Hogwarts, but it's something unsavoury ... oh, Severus Snape is definitely not a nice person and Albus knew it, but Albus was convinced of his loyalty, Albus was very sharp with Sirius when he said that he didn't believe that Severus had reformed, very sharp with him for provoking Severus in the kitchen at Headquarters last year.

She begins to weep when she remembers poor Sirius, unjustly accused of betraying the Potters, unjustly imprisoned in Azkaban for twelve years, Sirius had been right about Severus, but Albus wouldn't listen to a word that Sirius had to say on the subject of Severus.

"He always hinted that he had an iron-clad reason for trusting Snape," she mutters, dabbing at the corners of her leaking eyes with a tartan-edged handkerchief. "I mean … with Snape's history … of course people were bound to wonder … but Dumbledore told me explicitly that Snape's repentance was absolutely genuine … wouldn't hear a word against him."

"I'd love to know what Snape told him to convince him," says Nymphadora.

"I know," says Harry, and she turns to stare at him, as do the others. "Snape passed Voldemort the information that made Voldemort hunt down my mum and dad. Then Snape told Dumbledore that he hadn't realised what he was doing, he was really sorry he'd done it, sorry they were dead."

She thinks, Albus believed that? Severus hated James, if anything he hated James more than he hated Sirius … and Remus puts her thoughts into words.

"And Dumbledore believed that?" Remus says incredulously. "Dumbledore believed Snape was sorry James was dead? Snape hated James …"

Harry has more to say, "And he didn't think my mother was worth a damn, either … because she was Muggle-born … 'Mudblood', he called her."

She thinks, oh yes, I heard about that ugly little incident, during the OWLs, I had words with Remus about that, as a prefect he should have never allowed things to go that far, it wasn't good enough that he finally stepped in and stopped James from taking Severus' underpants off. It wasn't like Severus to insult a girl, though, and he and Lily seemed to get on well enough when Horace teamed them together for the NEWTs, and come to think of it, the only girl he ever hexed was Bertha Jorkins and we all know why he did that, the nasty gossip she spread about Severus and Florence and what they were doing together behind the greenhouses …

And then she thinks, is that why he did it? Did Severus nurse such a grudge against the Marauders that he would wait twenty years for revenge? Did he join Voldemort and play the spy for so many years just to get revenge for schoolboy pranks? Though to be fair that unfortunate business in the Shrieking Shack was more than a prank, she and Albus had agonised for hours about it, Sirius had behaved very badly indeed, but if the truth had come out, it wouldn't have just been expulsion for Remus, it would have been worse, it would have been execution. A werewolf who attacks a wizard forfeits all rights and comes under the jurisdiction of the Committee for the Disposal of Dangerous Creatures, and Remus didn't deserve that, but Severus hadn't seen it that way, he'd been convinced that all three of them were in on it, it wasn't just Sirius' idea of a joke - and he has never forgotten it, from the look he gets on his face whenever anyone comments on how Harry looks just like James, with Lily's eyes, and the way he'd treated Remus the year that Remus taught Defence Against the Dark Arts, and from what Molly and Arthur have told her, if he'd duelled with Sirius last year in the kitchen at Headquarters, it wouldn't have been hexes in the corridors, it would have been to the death.

She remembers when she came back to Hogwarts to teach - when her Quidditch career ended, when her marriage ended – it was like coming home, coming back to the school where she'd been so happy. But Severus didn't look like he was coming home, that day in the staff-room when all the teachers had been introduced to the new Potions Master, he looked like he was in hell … and it's a thought that has troubled her before. Dear god, could Severus really have been so unhappy here?

"This is all my fault," she says, suddenly, looking disorientated, twisting her wet handkerchief in her hands. "My fault. I sent Filius to fetch Snape tonight, I actually sent for him to come and help us! If I hadn't alerted Snape to what was going on, he might never have joined forces with the Death Eaters. I don't think he knew they were here before Filius told him, I don't think he knew they were coming."

But what she's really thinking is that it's her fault for not keeping stricter watch over the Marauders, she was their Head of House and she should have kept them under more control, Sirius should never have thought for a minute that he could get away with something like that, something so monumentally stupid. The reckless, thoughtless boy! Far too often his charm and good looks - and the aristocratic Black name - got him out of trouble, it was no wonder that he'd thought he could do no wrong, it was disturbing to remember how unrepentant he'd been. Charm and good looks … Severus has never had those, and his family were nothing to be proud of, Muggles and criminals, he had to keep his half-blood origins a secret from his own House.

She thinks, if I had been firmer with the Marauders, it wouldn't have happened, and perhaps Severus wouldn't have joined Voldemort … but Remus says something that breaks this painful train of thought, "It isn't your fault, Minerva. We all wanted more help, we were glad Snape was on his way …"

She thinks, stop tormenting yourself, Minerva, not even Albus could fathom the mind of that cunning treacherous Slytherin snake, he fooled even Albus, Merlin alone knows how. This past year Albus wouldn't leave the castle unless he knew Severus would be here, in case this very thing happened, and I sent for Severus at once, just as Albus instructed me to do. Damn you, Severus Snape, you fooled Albus, and you fooled me, too, I thought you were actually pleased to see me when I got out of St Mungo's last year!