Snape came out of the stairwell at the top of the Astronomy tower and leaned against the doorway to catch his breath. A shadow moved over the stones, and his hand twitched reflexively toward his wand before he saw that it was a cat. Strays sometimes moved in, although the chaos that was student life usually drove them off after a while.
The cat leapt to the top of the low wall around the edge of the tower and settled there. It ignored him, even when he walked up behind it. Snape looked down at the narrow walkway around the observatory and then out past it at the sheer drop to the dark field far below. He leaned one elbow on the cold stone. The cat sat up and began to wash a paw.
Snape decided he really wanted to be alone, and gave the cat a sharp shove, sending it toppling forward off the wall.
He didn't bother looking down to see if it missed the walkway. The thud came quickly enough that he supposed it hadn't missed. It was, however, a much louder thud than he had expected.
"Ow," a female voice said rather thoughtfully. At that, Snape did look down, mildly appalled.
"Professor McGonagall?"
"What an observation." Below him McGonagall was getting to her feet slowly. She moved as though it hurt, but he couldn't see any visible injuries.
"I had no idea."
"Obviously." She brushed off her robe. "Cigarette ends. And I don't want to know what else." Before he could say anything else, she disappeared into the doorway at the foot of the stairs. He waited, and she appeared at the top after a minute.
"Sorry," he said.
"Are you? That would be a first."
"You're right, I'm not," he said. "But I wouldn't have done it if I'd known I was assaulting a fellow professor."
"As opposed to a harmless spot of cruelty to animals."
"Don't cats always land on their feet?"
McGonagall leaned on the wall, looking down at the indistinct blobs of grey that were the shrubbery at the base of the tower wall.
"I think if a cat went over the edge, it wouldn't really have to worry about its orientation when it hit the ground," she said.
"What are you doing up here?"
"Chaperoning. Sinistra has been complaining that too many students are using the Astronomy tower as if it were a cheap motel room."
"I understand that that's traditional."
McGonagall's mouth quirked in a smile.
"I'm sure you do."
"And in your days I suppose the entire student body was chaste and pure as the driven snow."
"In my days, Professor Vasili kept the Astronomy tower locked," she said mildly. She studied him for a minute. "You look terrible."
"I didn't know you cared."
"Just an observation." She sat down on the wall, and then looked at him sharply. "If you don't object?"
"Oh, not at all. The more the merrier."
"The school grounds are large, Severus, and you're welcome to go brood in any part of them you like."
"Go to hell, Minerva," Snape said without heat.
"Ah. The patented Slytherin charm."
Snape thought about joining her on the wall, thought better of it, and slid down the wall to sit on the tower floor instead. The stone wall was cold against his back, even through his robes. He leaned back against it gratefully. McGonagall was looking at him curiously, and he twitched his mouth into a sneer.
"I've often wondered, do they actually teach being insufferable in Gryffindor? Or is it merely a natural talent?"
McGonagall accepted the challenge.
"One would think it was a natural talent, since you don't seem to have any more patience with the first years than the older students," she said.
"I have every bit of patience with them that they deserve."
"Why ever did you go into teaching if you loathe it so?"
"On the contrary," Snape said. "I enjoy teaching. I loathe many of my students."
"Enjoy what, precisely?" McGonagall asked.
"Rewarding success. Discouraging failure," he said.
"Severely discouraging."
"I try to make a lasting impression."
"You're such a petty sadist," she said.
"I resent being called petty," Snape said. He cleared his throat. "There is also some satisfaction to knowing that if they pay attention, they may learn something that will save their lives."
McGonagall raised her eyebrows.
"An admirable motive? How you must hate to admit it."
"I have never made any apologies for my nature," he said, crossing his arms.
"Slytherins never apologize for anything."
"Neither do Gryffindors, because in their own minds they are always right."
"Aren't we being juvenile tonight." McGonagall plucked an errant cigarette end from her robe and dropped it over the wall. "Couldn't you sleep?"
"What did I say that sounded remotely like 'I want to talk about my feelings'?"
"I'll try to remember not to take your feelings into account."
"You're welcome to try," Snape said. "But I doubt it's in your nature."
McGonagall snorted and looked out into the darkness for a while without a reply. Snape tried to decide whether she was looking at the lights of Hogsmeade or at the stars low on the horizon.
"Godric Gryffindor was a fool," she said finally.
Snape blinked at her.
"Obviously you've learned the secrets of Slytherin House," he said after a moment. "Now I shall have to kill you."
"I won't dignify that with a response," McGonagall said. "And the particular foolish act I had in mind was allowing the creation of Slytherin House."
"I wouldn't imagine he had much choice in the matter. I understand Salazar Slytherin could be quite persuasive."
"Yes, and I imagine Godric was a bit of a pushover. But it's come back to haunt us. No, really, Severus. Even you have to admit that all the worst of the Dark wizards have been from Slytherin."
"Are you so surprised?" Snape said. "Look at what we have to work with."
McGonagall looked vaguely scandalized.
"Severus, your own first-years-"
"Are an unpleasant lot. I look at them walking over to the Slytherin table, preening or sulking or pushing in line, and wonder which of them will have graduated to poisoning the pumpkin juice by the time they're eighteen. "
"That's my point. We'd be better off without that sort. And before you say it, I'm not talking about you. You can make yourself unpleasant, but you have redeeming virtues. The best you can say for some of the Slytherin students is that they're generally punctual."
"Where would you send them, then?" Snape said, raising a questioning eyebrow. "Durmstrang? Or to tutors hired by the parents who raised them? Or do children not deserve an education unless they're good?"
McGonagall opened her mouth to speak and then seemed to think better of it.
"At least in Slytherin they learn something," Snape went on. "The arrogant ones learn that they had better acquire followers, because they will make no friends. The sulking ones learn that really no one cares, so they might as well stop complaining about the world being unfair and find a way to get what they want despite it."
"And the ones who push learn to push harder," McGonagall said. "That Malfoy-"
"Suppose you had him," Snape said. "Here he is, Lucius Malfoy's heir, eleven years old and sorted into Gryffindor. Let's assume for the moment that Malfoy senior isn't pulling him out of school at once. Can you teach him to be nice?"
McGonagall's mouth narrowed.
"I refuse to believe that the course of these children's lives is set in stone when they're eleven."
Snape rolled his eyes.
"Of course they're not. Some Slytherins go on to be pillars of the community, and some Gryffindors betray their friends and murder the innocent."
"You're a little obsessed, aren't you, Severus?" McGonagall said. "I believe we were talking about Malfoy."
"Malfoy." Snape smiled thinly. "Malfoy is selfish to the core, and there are people who are all too ready to promise him anything he wants as soon as he's old enough to use. And the only thing he might hear that might keep him from throwing his life away for the Dark Lord is that it's a pathetically stupid thing to do."
There was silence for a while.
"I don't like it," McGonagall said finally.
Snape sighed.
"In my experience, Gryffindors rarely like the world we live in."
McGonagall smiled, lifting her chin.
"We try to make it better."
"And what do you get for it?"
"Sometimes, a better world," McGonagall said. "And then sometimes we get to argue with Slytherins in the dead of night at the top of a tower covered in rubbish. It's quite a mixed bag-"
McGonagall stopped short. There was a change in the quality of the light, from the silver of moonlight to an aged gold. In the eerie light, the tower took on the look of a woodcut on an aging page. Anyone might have created an alarm system only visible to the staff, but only Dumbledore would have bothered to make it beautiful.
"Here we go again," McGonagall said. "It's been happening all summer."
"Someone is very persistent," Snape said. "Or enjoys getting a headache trying to Apparate onto the grounds."
"And no one tonight said anything that might-"
"No," Snape said. He was getting a headache himself. He got to his feet, brushing off his own robes. "We should try again to trace its source."
McGonagall shook her head.
"Dumbledore's tried. We've all tried. Without any luck."
"It's no wonder, if luck was what you were counting on," Snape said. "Perhaps this time you could apply more skill."
"What do you want, Severus? A duel?" McGonagall smiled wearily and turned up her hands. "I really think we're getting too old for that, don't you?"
"Speak for yourself," Snape said. "I only feel as old as you."
McGonagall frowned at him.
"The thing about never being nice," she said carefully, "is that it makes you very hard to be nice to."
"Watch me weep," Snape said.