Harry lowered his hand, staring at it as though he expected it to come away from his forehead dripping with poison. He exhaled a slow, shaky breath, and fell limply into the nearest armchair. Snape glanced at him, but looked quickly elsewhere, and sank into the other chair – not the Headmaster's seat, but the one on the other side of the coffee table.

“Why are you telling me all of this?” Harry suddenly asked, looking over at Snape. “Don't you want to win the war? Even if – if you don't hate me anymore?”

Snape sighed and pinched the bridge of his nose with his free hand. “Harry,” he breathed, “This may be difficult to believe, but I never hated you. I never even knew you – not until today. I could not know you, for both our sakes. Do you understand me?”

Harry found, surprisingly, that he did. “You mean, you hated my dad. And I look a lot like him, and so you thought of me as another one of him, another James Potter, right? So all this time, you didn't know me for me – you just thought of me as his son. I know that – and I saw the bit in the Pensieve in Fifth Year, and he was a right berk to you, I know. I don't blame you for hating him – or me, really. I mean, I don't think I could treat Malfoy's kid completely fairly, even if he turned out all right.”

Something in Snape's expression softened almost imperceptibly. “You are more astute than I had thought,” he allowed, very quietly, “though perhaps, given what I do know of you, I should not be surprised.”

Harry wasn't sure what to make of this last; it sounded like a compliment, though he would have expected Snape to be the last person to offer one – but given recent events, he was not so certain of that, either. “Umm... thanks?” he ventured, “I think?”

“It was not meant as an insult, if there was any confusion on that score,” said Snape, with a quirk of his lips. “Far from it.”

Harry looked away, not quite able to meet his eyes, and asked, “Anyways, why'd you tell me about the Horcrux thing? I thought you wanted to win the war.”

“The Headmaster and I, you will find, have very different definitions of victory, and very different goals. Surely you do not think I renounced my Death Eater ways out of some purely altruistic motive?”

Harry snorted. “Yeah, honestly, you don't seem like the 'for the good of the wizarding world' type. So, there's something you want out of all this?”

“Indeed. I assure you, my reasons were completely selfish. It so happened that the very personal mistake I wished to right proved to be an unprecedented opportunity for the Headmaster,” the man sneered, darting another venomous look at the portrait.

Snape glanced back at Harry, and his anger dissipated completely. He took a deep breath and said, “Your mother, Harry.”

“Erm... 'scuse me?”

“While I attended Hogwarts, as you well know, your father was my worst enemy. What you did not know is that your mother... was my best friend.”

“What?” Harry spluttered, “but you were a Slytherin!”

“And is Miss Lovegood not a Ravenclaw?”

“That's different,” said Harry. “Slytherins are – well, um, different.”

“Articulate as always,” replied Snape, with a small smirk. “I grant you that Slytherins are rather more insular than the other houses, but not all of us, you will find, are Death Eaters. I am not the only Slytherin member of the Order of the Phoenix, for example, and I believe there is a very small minority of Slytherin Aurors. But I digress,” said Snape. “I knew your mother before we ever attended Hogwarts. We were acquainted growing up in a Muggle neighborhood.”

“You grew up with Muggles?”

“Yes,” said Snape, looking as though he had swallowed a lemon, “we lived in a Muggle neighborhood. It is not common knowledge – and I would prefer it remain such – but my father was a Muggle.”

“Yeah, I know that,” said Harry, “what with the 'Half-Blood Prince' and all, but I thought – your mum –”

“– was a witch of some power but little will,” said Snape, rather coldly. “You do understand that it would be a significant setback to our cause, should this become widely known.”

“I promise, I won't tell anyone. But Voldemort –”

“He knows, of course. It is difficult to conceal anything from him – I only lie to him when absolutely necessary. It is completely true that I despised my father, and it required very little imagination to conclude that I therefore must hate all things Muggle. He, too, is halfblooded, as you should recall, so he was rather... sympathetic, if you will.”

There was a pause as Harry thought about it. “You know,” he said, “that actually makes sense.”

Snape smirked. “I am gratified to hear it.”

“Right," said Harry. "But... what about my mum?”

Snape started and stared at him – through him and past him – and for a fleeting moment, Harry was reminded of the way Sirius sometimes looked at him, when he thought Harry wouldn't notice. Then Snape tilted his head, his hair falling forward, and the resemblance was lost.

“She was my friend,” said Snape, turning his gaze towards the window, “my best and only friend, throughout my childhood and while we attended school. I had allies in Slytherin, to be sure – I kept my parentage a closely guarded secret, and was in any case valued for my skill in potions and dueling, among other areas – but I did not have friends. Would not have had friends, had Lily not stubbornly clung to our past association and insisted that she did not mind the outcome of our Sorting.” The hard angles of Snape's face seemed to soften a bit as he spoke. “I recall she was terribly displeased with the Hat for a time – she wanted to be in Slytherin, because I was virtually guaranteed to be Sorted there, but the Hat wouldn't budge.”

“I asked it not to put me in Slytherin,” Harry said suddenly. “It wanted to, but all I knew was that Voldemort was a Slytherin. Umm – no offense or anything.”

Snape glanced sharply at him. “It is understandable,” he said. “I would have done the same, in your place.” He sighed, and added, “I asked for Gryffindor, if you would believe it, and was denied.”

“Wait, what? Why?”

“Did I ask? Lily was Sorted before I was.” A brittle smile briefly touched Snape's lips. “Our lives – the war, even – would have turned out very differently, had my request been granted.”

“But you said you two were still friends, even though you weren't in the same House.”

“We were, for a time. Our opposing House allegiances did, however, make that friendship significantly more difficult. Slytherin, even today, is not known for its tolerance for Muggleborn students. You can imagine it was much worse in my day, with the Dark Lord at the height of his power.”

“You were friends with Malfoy's dad, weren't you?”

“He was an ally, for all that he was several years ahead while we attended Hogwarts. He and his ilk were in the habit of making light of my friendship with your mother. She did not particularly mind; she was always a singularly obstinate person.”

“But, then, what happened in fifth year?” At Snape's raised eyebrow, Harry added, “I mean the part I saw in your Pensieve. Sorry about that, by the way. Really, I didn't really know – ”

“It is in the past,” said Snape, and for a moment, Harry could not be sure whether it was to his mother or to his own transgression the man was referring. “I should have, in retrospect, taken more stringent precautions. You were always unhealthily curious – I have known that since your first year – but I digress. By fifth year, I had largely fallen in with the wrong crowd, so to speak – many of my associates would go on to become or marry Death Eaters. Ultimately, Lily presented me with a choice. I chose – well, you can infer how I chose. Slytherins are not well known for their courage.”

“I mean, I don't really blame you. It's not like you could choose her and everyone in Slytherin would be fine with it – they'd have made your life kind of miserable,” said Harry. “But that time after your OWLs – you didn't have to call her a Mud–”

“Don't say it,” Snape snapped, showing the barest hint of uneven teeth. “It was a mistake, one in a long history of terrible mistakes. I said it for the benefit of your father and his friends, to remind them that I had powerful allies, for all that I was usually outnumbered. By then, some of my staunchest allies – including Lucius Malfoy – had graduated, so I was even more a target than in previous years. It also particularly rankled Black, seeing as his own brother was another of my very few friends.”

“But you said it to my mum!”

“I know,” said Snape in a fierce almost-whisper. “Do you think I would have, were it not for the circumstance? Believe me, I hardly knew it was Lily at the time, and I have regretted my teenaged impetuousness for twenty years thereafter! If only – had she not – washed her hands of me, if I had not driven her to it, we might not be in this... situation, today.” Snape exhaled, and Harry fancied there was something small and broken in his breath. “After that day, I had no real reason to distance myself from the more unsavory of my allies' activities. I took the Dark Mark within a week of my graduation.

“The Headmaster has assured you time and again of his confidence in me, in my loyalties; what he did not tell you, perhaps out of a misguided attempt to simplify for you our rather complicated history, is that I was not always his. I was once a genuine Death Eater. I did not shrink from Dark Arts; I was one of the most proficient in his circle. I have killed for him, tortured for him – I am not proud of it, but I did, and still do.”

“You do what you have to do,” Harry said, “to, umm... keep your cover.” At Snape's appraising once-over, Harry added, “No, really, I get that. I was almost a Slytherin, remember?”

“Indeed,” replied Snape, his thin smile not quite reaching his eyes. “I can only hope you will be similarly forgiving, when you have heard the rest of it. Did you know that I overheard the prophecy Trelawney made at the Hog's Head?”

“No – wait, I think Trelawney might have mentioned it to me once. Why – I mean –” Harry cut himself off, suddenly, feeling as though his stomach had fallen through the floor. “You told him,” he said in a vaguely horrified way, the blood pounding in his ears. “Voldemort. That was how he found out about it.”