Harry blushed and turned away. But how to stop them? Hermione could get in real trouble being out here after hours, he reasoned. If Filch catches them, she'll get detention, and if he spreads the story around she'll never hear the end of it. I'm doing this for her own good, he thought, and raised his foot to make a noise.

He didn't have to. With a loud creak the portrait hole swung open and two figures slipped out. In the silence he could hear them whispering.

"That was a piece of cake! He wasn't even there!"

"Probably out snogging somewhere with Cho Chang. If you see him on the map, just pretend not to notice – marauders' courtesy and all that."

"Right, it's not our company he'll be wanting." Harry recognized Fred's chuckle, just a bit more raucous than his twin's.

"Good thing the Sneakoscope didn't wake anyone up."

"Yeah, you grabbed it just in time. OK, now where to?"

"Back to the dungeons, I guess. We have to find that secret passage. Ron said that you just walk through a wall, but he didn't remember where. Shall we try the corner stairwell this time?"

The twins set off down the hall. Forgetting Hermione and Crabbe, Harry followed as quietly as he could. He was furious with them for taking the map without asking, and knew they would have taken the cloak as well if they had found it. They turned right toward the near stairwell and climbed to the second floor corridor, darting from one statue or suit of armor to the next like soldiers in enemy territory. Pale moonlight filtered through the transoms above the doors, enough that Harry did not have to light his wand. As he approached Takushiki's office the Sneakoscope went off again, making them all jump. Both twins grabbed at it and missed, fumbled for it, chased it along the hall and finally quieted it. It would have been hilarious if they weren't in such danger of being caught. He heard them arguing in hisses as he caught up to them.

"Why'd it do that?"

"I don't know, it was just outside Sugar Lips' office."

"Wait a minute, remember what's in there?"

"Right. Our little note paper. Filch must not have emptied the rubbish yet."

As they hastened to the next statue, Harry ducked inside the empty office. The crumpled pink notepaper lay at the top of the dustbin. He unfolded it and silently read,

Dearest Argus, my heart cries out for your tender love…

The rest was a mass of cross-outs and erasures. That is so cruel, thought Harry, jamming the note into his pocket. He peeked out of the door and seeing all clear set off after the twins again. At the corner stairwell he had to feel his way downwards, past the double trip step four treads down from the first floor, into the dungeons. A flash of light in the stairwell told him that they were in the second level below ground. He turned the corner to find them checking the Marauders' Map.

"Magnificat, magnificat, magnificat, magnificat.. OK, can you see it now?"

"All right, I'm not blind. Is that it? It's awfully small – don't tell me Marcus Flint ever fit through that."

"Oh rats, look, it's one floor above us, near the Potions lab."

"Still, I'll bet that's it, it must be. Come on, I'll prove it to you." Harry pressed his back against the wall as they trotted past him and back up the stairs. Their wand tips bobbed up and down the corridor in front of him, casting ghastly shadows on the damp stone walls.

"See, I told you. It's right here. It must be behind the student supply cabinet here. That's Snape's office on the other side."

"Wait, Fred – isn't it kind of funny we never saw this before?"

The other figure slowed down and shrugged. "You know how things move around in this place. I'll bet even Snape doesn't know it's there. Let's go back to the second level." They prowled past him and back down the stairs.

Harry had never been so deep in the dungeons at night. The musty odor was overpowering. Luminous patches of fungus at the base of the walls gave off a greenish glow, enough to indicate the passageway, but too faint to see by. He wondered uneasily what it was that felt so sticky under his socks. Far ahead of the twins' wands, a shadow moved in the stairwell. A cloud over the moon? thought Harry – but then he saw it change direction.

The twins had seen it too. They doused their wand-lights and huddled into a niche in the wall – a damp one, judging from the muted hissing and pushing sounds that issued from it. The light grew brighter and suddenly shone full in Harry's eyes. It was Crabbe, wide-eyed with anxiety, searching back and forth with his wand-light until he came to a bare spot of wall. "Noble destiny," he said, his voice trembling, and plunged through it.

"All right – we've got them!" The triumph in Fred's voice was unmistakable.

"Wait – before we leave, let's make sure we know where we are."

"OK, OK. Down the corner stairwell from Potions, take the hall on the left, opposite this little bay with the pillars… Look, there's even a snake carved on one of the stones."

Harry crept up behind them into a scene he vaguely remembered from his adventure with the Polyjuice Potion two years earlier. Just opposite the hidden entrance stood an open, semicircular room with a high ceiling and stone benches. Fog swirled around his feet. He smelled fresh air and looked up to see windows at the top, completely frosted over with the dungeon's dampness.

"Let's get out of here, Fred, we have what we came for," said George, sounding worried.

His brother nodded, and they moved back toward the stairwell, coming out again several flights higher up, on the second floor. They had just stepped into the corridor when a flickering light appeared in front of them.

"Rats, it's Filch – that's his candle. He must know someone's out here. We'll have to go around the long way." They changed direction and resumed their surreptitious progress from one statue to the next, alternately in dim light and darkness as clouds passed over the moon.

"Hold on, what's that up ahead?" Creeping closer, Harry could see the Headmaster's office brightly lit. George and Fred crawled past the door, pausing momentarily to peer through the keyhole. They passed and Harry took a turn. Wrapped in the invisibility cloak, he could look straight in through the door glass.

Snape was at his desk, quill in hand, surrounded by stacks of papers. The flat wooden box lay open in front of him. He looked haggard, and deeply frustrated. Serves him right, thought Harry. He wanted this job, and now he can't handle it. Tough luck. Suddenly Snape jammed the quill into the inkwell and stood up. Instinctively Harry backed away, but Snape remained standing at his desk. He clenched his fists, then put them to his head. "Why can I not understand?" he demanded aloud, his voice grating. Harry saw a motion above his head; one of the portraits had awakened and was gesticulating to the others. Snape began to pace around the office, first to the window, which he flung open, then to the door, staring straight at Harry until his heart rose into his throat. He seemed to be looking for something.

Now you know what it feels like not to have the answer, you nasty old git, thought Harry. Finally Snape stopped in front of the bookcase and hesitated there for a long moment. His thin hand reached out for the Sorting Hat. Slowly, tentatively, he drew it towards him and placed it on his head.

It laughed.

A wave of fury passed over the Headmaster's face. "Insolent old rag!" He ripped off the hat, flung it on the floor and strode away. Above him, the portraits kept watch. After a few paces he stopped and turned back. He took a few deep breaths, controlling his exasperation, and put the Hat on again.

"Don't want to admit it, do you?" cackled the Hat.

Snape's voice fell to a whisper. "That was years ago. Half a lifetime. I was an idiot and I've been paying for it ever since."

Then it's true, breathed Harry. You were on the Dark. You're still on the Dark.

"Are you sure? Don't deceive yourself. It was also the best thing that could have happened to you. Turned your life around. Look at you now, Headmaster of Hogwarts."

"You know that's not what I wanted."

The Hat chuckled again, sardonically. "You'd be surprised how often I've heard that from your predecessors. Oh, I know all about it. You want to direct the Institute of Potions. Have your own research laboratory again; work on the potions of your choice."

Harry's stomach clenched as he remembered the odor of Dumbledore's potion, and the hot feeling of the old notebook. Potions of your choice.

"Have a little patience; Lucius will fix it for you. He has some fascinating things under his drawing room floor."

"No!" Snape hissed. "That carrion – I can't abide the way his darkness…reaches for me."

"You weren't always so particular. But do it your own way. You always did. If you're too proud to ask Lucius, figure it out for yourself. You should know by now how Old Red-eyes thinks –why is he killing Squibs?"

"Because, because…I don't know!" Snape burst out.

"Don't deceive yourself – you know very well," the Hat scolded. "What was it he told you when he gave you old Grindy's potion notebook?

Snape looked down. "No intellectual effort is ever wasted," he said reluctantly.

"Then don't waste it. It's all here in your head, you know, and you can't hide from it any longer, not after that day in Defense class, the rumours are all over the school by now…"

"Don't torment me!"

"No one's tormenting you but you. Go get some fresh air. Have a look out the window. You can bear it, now that the windowsill's been replaced. Take it a little at a time…"

"Ahhhh," breathed Snape. "That's it, how could I have missed it? That's what he's up to."

The Hat sniffed. "Good lad!" it exclaimed sarcastically. Snape's lips thinned. "Now what will you do next?"

"I suppose you can see that in my head too?" growled Snape.

"Nope," said the Hat cheerfully. "Try me again in a week or so. Meanwhile, wash your hair. Like it or not, you're Headmaster now, and if you want any respect from Malfoy, you'd better act the part."

Snape began to pace again, steadying the hat with one hand. "I must discover where the Dark Lord is and what his next action will be," he mused aloud.

"Lucius will tell you when he's ready. Or you could ask, couldn't you? You two are such good friends. Isn't he always ready to do you a favor?" asked the hat with singsong mock innocence.

"He asks questions, he doesn't answer them, as you know perfectly well," retorted Snape.

"As well as you do? When are you going to tell him what was in that potion?" The Hat sniggered. "The two of you are like a couple of squabbling schoolgirls. Always playing catty little head games with each other. You just love those games, don't you? You can one-up any student in the school, you put Remus Lupin in his place last year, but this time, boy-o, you've met your…"

Snape snatched off the Hat and flung it back on the bookcase. The broad rip in its brim grinned widely for a moment and then it was still.

Just then the Headmaster froze, as if listening to something. Harry heard it too, off to his left: quiet footsteps, first running, then pausing. Whispers echoed along the corridor to him.

"So, where else do you have them hidden?"

"I don't. That was the last one. When Filch hears old Sourpuss yell I guarantee he'll come running."

"Right, then we can get back to the dorm."

Harry turned to his right. Was he imagining it, or was someone else there? The other footsteps sounded and he took the opportunity to edge across the hallway, away from the door. Suddenly Fred was right in front of him, peeking through the keyhole, George at his back.

"He's still at his desk. I'll open the door, and you throw it in."

"On the count of three. One, two, …"

Without warning, the Sneakoscope went off. There was a loud yelp, and Filch jumped out from behind the bench in the corridor. "GOTCHA!" he shrieked, seizing a struggling Fred around the neck. Without hesitation, George grasped the back of Filch's collar and jammed something down into his shirt. "Hey! what? what?" Filch cried, dropping his prey and turning around wildly as the twins pounded away down the corridor. Now Snape was at the door, now he was turning the knob, and – POOF! – a rich stench filled the air. The dungbomb had burst open. "Aaah! You limbs of the Dark!" howled Filch, coughing and choking. Ignoring him, Snape ran down the hall after the twins, wand in hand. Harry followed, barely keeping up with Snape's long stride. He couldn't let the twins be caught – they had his map and his Sneakoscope, and if they were expelled, as now seemed likely, he might be too. Snape's heavy footfalls echoed in the dark corridors and up the stairwell. Arriving on the fourth floor, Harry saw the twins disappearing around a corner to the left. Snape pointed his wand and began to mutter. The noise of footsteps started off after them as Snape ducked behind a statue, panting.

Oh no, thought Harry, he'll get them as soon as they come back around. He began tiptoeing down the corridor to the right, as quietly as possible. He didn't remember ever having been in this part of the castle. Instead of windowed classrooms, small storage rooms and narrow hallways led off the main corridors. How would he find the twins in such a maze? Then he heard whispering.

"Fred – this one's open! Let's hide out till he goes away."

"Are you kidding? What if he locks us in?"

"We'll jimmy the lock. Come on." Followed by Harry, they slipped through a short open door into a small room filled with heavily draped furniture. They scurried behind a couch and doused their wands.

In the pitch darkness Harry could hear two sets of heavy footsteps approaching. "Get some rest, professor," said Filch's voice. "There's always a next time with them two." He coughed. "Ugh. I'm going back to have a wash."

"As you please, Filch."

Harry listened until the steps died away. Then he heard them again. One person, coming closer, slowly, haltingly.

The door opened and Snape ducked through, his wand brightly lit. The candle brackets around the walls flickered into brightness as he entered. He advanced toward a tall, round-topped object and flicked away the draperies.

It was the Mirror of Erised.

Snape drew in his breath sharply. "Headmaster…" he murmured in a fading whisper. He looked away for an instant, drew out his wand and pointed it sharply at the mirror. "Show me the Weasley twins – I want to catch them," he commanded. For a long, tense moment he stood there; then his shoulders slumped. "Damn…" Pressing his lips together, Snape thrust his wand away into the folds of his cloak. He took a step toward the mirror and placed his hands on both edges, gazing deeply into it.

When he spoke again it was in a low voice: "I suppose most people look in this glass to see the future of their dreams. I only see a past that never happened. I wish I hadn't gone to Knockturn Alley. I wish I had never met Lucius Malfoy. I wish I hadn't given you that potion. But I did… I did, and now I have to live with it." He drew back, grimacing, and straightened his robes angrily. "You're a dream, that's all. A nightmare. Why should I want to see you, Dumbledore? I was never your golden boy. That was James Potter. Well, I paid you both back, didn't I?"

Snape snatched up the drape and twisted it in his hands. His whisper turned fierce. "Idiot mirror. All you can show me is lies. There's no logic in you. Goodbye, Headmaster." He threw the drape over the mirror and strode out, slamming the door behind him. Instantly every candle flickered out.

In the blackness, Harry leaned against the wall, near tears. What a mockery, he thought. He murdered Dumbledore, he wrecked his plan, and now he wants to be forgiven. He blinked as the twins flicked on their wand-lights and silently crept out from behind the couch.

"What on earth was he talking to?"

"S'got to be that Erised mirror Ron told us about. Took all the starch out of him, didn't it? Did you hear him admit everything?" George shook his head wonderingly.

"I only wish Fudge had heard him – th'old git would be on his way to Azkaban right now."

"Say, Fred – shall we have a look for ourselves?" Holding up their wands, the twins pulled down the drape and looked into the mirror's depths.

"What do you see?" asked George, a bit nervously.

"You first," Fred retorted. "I bet you have Sugar Lips, don't you? 'Fess up, George, my boy."

George laughed. "No, I see us… we're in a dungeon… wait… it must be the Slytherin common room…"

"And we're painting it!"

"Red and gold!" The two slapped hands. "We've got to do it. Can't you just see their faces?"

"Let's do it, then. Shake?" The two clasped hands - and the Sneakoscope went off again.

Harry crouched in the dark, listening until their footsteps died away. Then he ran back down the empty corridors to the common room, his heart pounding.

He scrambled through the portrait hole and threw himself into a chair, furious.

" 'I was never your golden boy!' Oh, poor little Severus, it was everyone else's fault that you were a mean git. I suppose it was my father's fault you went bad and betrayed Dumbledore and ended up a murderer! And now you're feeling guilty and you're worrying about what Voldemort's up to and what little job he's going to make you do next! Because he must know what you were up to all those years ago. I bet he was right there with you. Well, it's too late for you to have cold feet. But don't worry, he won't win. You won't win. My father beat you every time and when it's my turn, I'll beat you again."

A/N: Pogonia is traveling this week so the next update will be in a week. Please review - it's lovely to hear from readers.