"Scabbers! Get away from him, you filthy mutt!" Ron screamed, running as quickly as he could after the big black dog, who was chasing the rat and growling horribly, as if he was going to tear the rat to pieces when he finally caught up with the scurrying rodent.

Scabbers ran with the speed of the damned, moving quicker than he ever had in all of his eleven years, darting for the supposed safety of the Whomping Willow, for there was a secret passage beneath its roots known only to a select few who had once attended Hogwarts.

The tree stirred, its branches swaying in warning, but the rat ignored them, slipping between the thick roots to press a hidden knothole with his paw. A creak and a dark opening gaped wide, and Scabbers fled down the secret way that was revealed.

The black dog howled and bolted after the disappearing rat, only to be brought up short when Ron dived on him and grabbed his tail.

"Get off! Leave him be, you mangy mutt!" yelled Ron, struggling to hold onto the big dog. "Just leave him alone, you bloody beast!"

But the dog was not as thin or weak as he had first appeared and he turned upon the boy with surprising speed, his jaws closing over Ron's arm and biting down hard.

"Ahhh!" Ron screamed, releasing the dog's tail.

"Ron! What happened?" called Hermione.

"The stupid damn dog-it bit me!" cried the red-haired wizard. Then he latched onto the dog's leg as it tried to run away.

This time the dog did not bother trying to shake off his persistent pursuer, but just ran at the gaping mouth of the tunnel beneath the Willow, dragging Ron after him.

"HELP! HERMIONE! HARRY!" Ron shrieked, as the dog dragged him into the mouth of the tunnel.

"Ron!" screamed Hermione, and threw herself on the ground and grabbed Ron's foot just before he disappeared into the black maw. She was then dragged right after her friend and just as her foot cleared the entrance, the tunnel closed with a snap.

Harry and Aria arrived soon after, but found no trace of them. "Huh? I heard them screaming, so where are they?" panted the professor's son, looking about wildly.

Cougar Aria paced wildly, lashing her tail and growling. The Willow's branches trembled, disturbed by the big cat's presence.

Then there came a soft mew and Crookshanks appeared out of the darkness. The ginger cat ran between Harry's feet straight to the roots of the Willow and tapped a knot with his paw.

The Willow shuddered and froze, and the secret tunnel slid open again.

"Clever cat!" Harry praised. "So that's where they went. Thanks, Crookshanks." He glanced back at Aria, who had transformed back into a girl. "You coming, Lupin?"

"Damn straight, Snape. Somebody has to be there to save your idiotic Gryffindor hide."

Harry grinned at her. "Spoken like a true Slytherin." Then he slid into the tunnel and Aria followed.

They landed with a thump in a dusty room with bits of broken furniture and cushions scattered about. Harry lit up his wand and discovered that the door and windows had been boarded over, and the only exit seemed to be a set of rickety stairs where they could see trails of small footprints and a dog's paws in the thick dust that coated everything.

"Where are we, Harry?"

"Uh. . . .this was a tunnel marked on the Marauder's map," Harry said quickly, recalling then the existence of the tunnel, and also the story his dad had told him about going to the Shrieking Shack and finding Moony in werewolf form. He glanced at the wall opposite the door and saw a rusted chain buried in the wall attached to an iron manacle. "Aria, we're inside the Shrieking Shack."

"In Hogsmeade? But how?"

"The tunnel led us there. This was where your uncle used to be locked in when he transformed. My dad told me the story."

"About how Uncle Remmy almost bit him?" Aria clarified. "He told me that one too. He said he was sorry and he felt awful, but the were nature was too strong and he couldn't help himself."

"I know. It wasn't his fault, it was Sirius Black's." Harry said, his eyes flashing. "Just like it was Black who killed my mum and James." He started to follow the trail of footprints up the stairs.

At the top was a short hallway with three rooms, but only one room was open. Harry crept down the hallway and peered into the room, seeing a large fourposter bed where Ron was sitting, holding on to a trembling Scabbers, nursing a bleeding arm and a sprained ankle. Hermione was on the floor, bleeding from a cut to the head and looking like she'd been knocked out.

"Ron! Are you all right?" Harry cried, coming into the room. "What happened to Hermione? And where's Black?"

"Harry! Behind you!" shouted Aria, just as a large dog jumped on him, knocking him flat on the floor.

The dog growled sharply as Harry struggled, but the animal was too strong and he was only a skinny small thirteen-year-old.

Then came a low snarl and suddenly the dog flew against the wall as Aria leaped into the room, filling the small space with her cougar shape.

Harry got to his feet, wincing at his scraped knees but he had his wand out and pointed at the dog, who was shaking its head and getting to its feet. It bared its teeth, but did not attack, instead watching Harry and the cougar warily.

Aria's amber eyes were blazing and she curled her lip and wailed the cougar war cry, her muscles tensed to spring, ears flat against her head.

The dog whuffed at her, curious. For a moment amber eyes met brown ones.

Then all at once the dog was gone and a tall man with tangled wild black hair and eyes tinged with fury and disbelief was standing there. He looked like a refugee from a concentration camp, all skin and bones and his dirty shirt and graying pants hung on his skinny frame like a tent.

"You won't hurt me, girl," he rasped softly. "It's forbidden for an Animagus to harm a human. It's the Third Rule in the Shifter Code."

"How do you know that's not a real cougar?" Harry demanded, glaring at the criminal known as Sirius Black.

"I'm an Animagus, and I know my own kind," answered Sirius evenly.

The cougar curled her lip in a feral smile. Then she transformed back into a girl, saying softly, "Then you don't know as much as you think you do, do you, murderer? Because I'm no Animagus. I'm a shape-slipper."

Black's eyes widened. "A shape-slipper. That's a rare talent, you're the first one I ever met."

"First and last," Aria said softly, her amber eyes glowing angrily. "You gonna come quietly, Black? Or do we have to get rough?"

Black laughed softly. "Brave words, little girl. But we both know you'll never harm me in your cougar shape. The laws forbid it, and you're a shifter, and therefore bound by them."

"I'm not," growled Harry, advancing on the other man. "I can kill you right now, Black. And I will!"

Sirius turned to look at him for the first time and gasped. "Merlin! You look just like Snape! Except your eyes. Those are-"

"-my mother's," Harry finished grimly. "And you killed her, you traitorous bastard! You betrayed Lily and James to Voldemort and now you're going to pay!"

"I never did!" protested Sirius. "There was another who betrayed us all and he escaped that day from me, but never again. Now I've found him and he'll pay for killing my cousin and my friend. You've got to believe me, Harry!"

"You're a damn LIAR!" Harry shrieked, boiling over with rage. "You doublecrossed them and made a pact with Voldemort, you dirty stinking coward son of a bitch!" He was trembling with rage, so furious he could barely see, his wand blazing with pent up magical energy. "Miserable bastard, I'm going to blow your sodding head off!"

Sirius whistled. "Hell, kid, guess you still remember all the swear words I ever taught you, huh? Good thing Lily or Severus isn't here to listen to your mouth, boy, you'd be eating soap in two seconds." He held up a hand. "Lower your wand, Harry. There's only one person who deserves to die here tonight, and it's not me."

"Why not?" demanded Aria sharply.

"Because I'm innocent," Sirius said calmly.

"There were witnesses."

"Who saw something they were made to forget."

"Yes, they saw you kill thirteen innocent people and Peter Pettigrew!" cried Aria.

"No. They saw Peter kill thirteen innocent people, and try to kill me," corrected Sirius softly.

"Why should we believe you?" growled Harry.

"Because for once in his life, he's telling the truth," answered Moony from behind them. "Hello, Padfoot. Long time no see."

They all whirled around and saw Remus standing there, looking rumpled from sliding down the chute-like tunnel, holding the Marauder's map in one hand and a wand in the other. He was frowning ferociously and Aria cringed.

But his gaze was not on his disobedient niece, but the rat clutched in Ron's arms.

"You can't hide anymore, Peter. What was hidden away has now been found, and the truth will out," said Remus grimly.

Ron looked from one wizard to the other in utter puzzlement. "Huh? You've all gone barmy! Lost it completely. This is Scabbers, my rat, not-not a dead wizard or whatever! What's the matter with you people?"

"No, Ron. That's not Scabbers," Lupin said softly. "Or rather Scabbers is also Peter Pettigrew, my old school chum, whom we all presumed dead these eleven years. Only that was a lie, wans't it? Because the map showed me the truth." He tapped the map with his wand. "You couldn't fool it, Peter, not even in Animagus form. I couldn't believe my eyes when I checked the map and saw your name upon it, right next to Ron's and Sirius's. I thought I was dreaming. So I had to come and check it out for myself. And the map was right."

"Impossible! He was my pet for eleven years!" Ron cried. "He's not Pettigrew!"

* * * * * *

Severus was dreaming he heard Lily calling him. "Sev, wake up. Go and get Harry, it's your turn tonight. C'mon, love, wake up, the baby's crying." Severus groaned, trying to shut out the insistent howling, but it wouldn't go away. "Severus! Get up now!"

"All right, Lil, I'm up, damn it!" he cried, sitting up on the couch and rubbing his eyes. "There's no need to shout . . .in my ear," he trailed off when he glanced around and discovered he was not in bed with his wife, but on his own couch in the Potion Master's quarters, and a beagle was baying loudly in his face.

"Rosie! Bloody hell, dog!" he swore, pushing the beagle's face away from him, for she was licking his entire cheek. "Must you give me a bath every time you see me, you pest? I wash my own face very well, you silly beagle." He wiped his cheek with his sleeve, grimacing. "God only knows where that tongue of yours has been, dog."

Rosie barked and whimpered, looking pointedly towards the door.

"All right, give me a minute to get my shoes on, won't you?" he grumbled, shoving his shoes on and summoning the dog's leash. "I'd have thought you could have waited until Harry came home to go out," he told the dog, snapping on her leash and going to the door. "Heel, Rosie!" he ordered, before the dog dragged him out the door.

The quickest route to outside was a small set of stairs hidden near his quarters and he used these now, figuring the dog couldn't wait to go the usual route.

The stairs brought him out to a small grassy verge near the lake. Snape glanced at his watch as the beagle watered the grass, only then realizing that it had been an hour since Harry had left for Hagrid's and he still wasn't back yet.

Severus's mouth thinned in disapproval. "Damn that child! Doesn't he know how to tell time yet? I said one hour and it's now an hour and ten minutes. I warned him not to be late or else!"

Rosie had finished her business by then and Severus led her down the path to Hagrid's cottage. "Come along, Rosie. Let's go and fetch your forgetful master home, where I can ground his sorry arse for another week for breaking his promise to me."

Rosie bayed and raced happily down the path, tugging Severus along.

"What do you mean, he's not here?" an exasperated and annoyed Severus demanded of Hagrid, who was drinking bucket after bucket of mead, but didn't even sound remotely drunk. "He was supposed to be back fifteen minutes ago."

"Uh, I dunno, Professor Snape. But I sent Harry back t'the castle some thirty minutes ago, I think, right b'fore Dumbledore left with the Minister. Is he missing again?"

Snape nodded curtly, fuming. "Don't worry about it, Hagrid. I'll find him. And when I do . . ." he trailed off, but the look on his face said it all.

"Ah, sir, don' be too hard on ‘im. He's a good kid, y'know," Hagrid began.

"Humph! That good kid, as you put it, is going to drive me to drink someday, Hagrid!" Severus said sharply. Then he added, more gently, "My condolences on the loss of Buckbeak. The Minister is an utter idiot for ordering the hippogriff's execution."

Hagrid nodded. "Thanks, sir." He opened his mouth to tell Professor Snape about the odd circumstances surrounding the hippogriff's demise, but Severus interrupted him.

"I need to be going, so I can find my son and go home before it gets any later. Good night, Hagrid."

"Night, Professor."

Severus sighed and then scowled down at Rosie, who was sitting at his feet, her tail switching the dirt. Then he got an idea and snapped his fingers, causing the little beagle to look up at him. "Rosie, can you find Harry for me? You're a beagle, you track rabbits, surely you can track my son. How about it, girl?"

Rosie was on her feet, tail wagging frantically.

"Good girl. Find Harry! Where is he?"

The beagle whimpered low in her throat and then sniffed the ground.

"Rosie, go find Harry!" Severus ordered, praying the dog comprehended his order. He'd never formally trained the dog to track people, but they had played a kind of hide and seek with the dog that she loved.

The beagle snuffled for a few more minutes, then bayed and took off, running to the full extent of the leash.

Severus followed, praying the beagle really was tracking down his missing son, who was going to be very sorry when his father finally found him, Snape vowed.

Rosie ran with the tireless lope of a hound dog on a scent, her floppy ears flying, sweeping the scent of her beloved master to her nose until her sensitive nostrils were filled with his particular scent. The trail was fresh, not even an hour old, though it was mingled with the disturbing odor of a big cat, and a strange dog, a cat, and a rat. But Rosie did not care about that. All she wanted was to do as Severus had commanded and find Harry.

This was like a new game of hide and seek, one of her favorite things to do, and she would not disappoint her Alpha-Dad by losing the trail. That was pretty impossible, the trail was so obvious a puppy could have tracked Harry. So Rosie ran on, wondering if at the end of the trail she would get a treat, the way she usually did.

Severus couldn't believe where Rosie was taking him. All the way across the lawn to the Whomping Willow. What in Merlin's name had possessed Harry to come out here? Rosie halted just before the tree, she knew how dangerous it was, it had nearly swatted her the first time she had gone near it.

She danced impatiently on her hind legs, baying hysterically. She could smell Harry down there, beneath the Willow's roots. But she did not know how to reach him. She gazed back at Severus, who smelled of concern, worry, and anger. That's your job, getting past the moving tree, the beagle whuffed.

"Down there? In the tunnel?" Severus demanded and Rosie bayed an affirmative. "Hell, beagle, what's he doing down there? Unless . . ." a cold chill skittered down his spine. What if Black had captured Harry? Black knew how to open the secret door, he knew to press the knothole that would freeze the Willow for a period of time, long enough to get down the tunnel and into the Shrieking Shack.

"Stay!" he ordered the dog, dropping the leash on the ground. Rosie obeyed, watching Severus intently.

Severus waited until the Willow was quiet, then darted in and slapped the knothole and the secret tunnel opened. "Come, girl!" he called, and Rosie barked and ran to him.

He scooped her up then slid down the tunnel.

They hit the bottom and Rosie sprang out of his arms and sniffed, then raced up the stairs, the leash dragging in the dust.

Severus dusted himself off and went after her, silent footed as a cat, wand out.

* * * * *

Hermione stirred, groaning softly. Remus moved to her side, summoning bandages to wrap her head. But she did not speak and after a few moments lapsed back into that odd sleep.

"Is the girl all right, Moony?" asked Sirius.

Lupin nodded. "Yes, just a nasty bump on the head. But you certainly know how to make an entrance."

Before Sirius could respond, there came the patter of little paws and then Rosie thrust her dusty but keen beagle nose into the room and bayed happily.

"What the-?" began Sirius, staring at the little beagle, who frisked up to Harry and jumped up at him.

"Rosie?" Harry gaped at his dog. "How'd you get here?" he fondled the dog's ears, knowing perfectly well the last time he'd seen Rosie, she was asleep on the couch next to his father.

"This your dog, Harry?" asked Sirius. "Never figured Severus'd unbend enough to let you have a pet, much less a dog."

In Ron's arms, Scabbers was shaking, and Ron stroked the rat comfortingly, glaring at Lupin and Sirius.

"Amazing, now I've finally heard it all," drawled Severus, stepping into the room, his wand out. "The arrogant Black admitting he doesn't know it all. Maybe Azkaban was good for you after all, if it knocked all the bloody arrogance out of you."

"Look who's talking, Snivellus," sneered Black, glaring at his old schoolmate with dislike.

"Don't call him that!" Harry shouted, poking Sirius with his wand.

"No, let him, because I've got much worse to call him, Harry," said Severus silkily. "Like murderer and betrayer! Tell me, Black, did you laugh when she was gone, did you watch when your dark master went to Godric's Hollow and killed them?" The Potions Master edged into the room, wand pointed directly at Sirius, a look of utter hatred on his face that made Harry grow cold. "Did you know this one still remembers the moment his mother died, that he can still hear her dying scream in his memory? Does that amuse you, you bloody bastard?"

"I never killed Lily, Severus. Or James. Yes, you were betrayed, but not by me."

"Oh, and I'm supposed to believe you, Black? Your whole family was staunch supporters of Riddle, and you followed right in their footsteps."

"My family doesn't define me, Snape. Anymore than yours does you. Are you an abusive drunken bastard, Snape, like your father?"

Severus trembled with rage, looking like he was about to explode. "Don't you dare lie to me, Black! You were their Secret Keeper and you broke your oath and she paid for it! All of them did, even Harry almost died that night, and then you had the nerve to go hunting for him even now to finish the job your Dark Lord couldn't!" The tip of Severus's ebony wand pressed against Sirius's temple. "Give me one good reason, Black, why I shouldn't kill you here and now."

"Sev, don't. He's innocent," began Remus. "Listen to me."

Severus still kept his wand trained on Sirius. "What's this, Moony? What line did he feed you to make you think that? He murdered my WIFE! He deserves to rot in hell for all of eternity and by all the devils in hell, I'm going to send him there!"

Severus's eyes were blazing with eleven years of pent up hatred and anger, his mouth was flecked with spittle, and his wand hand was like a rock, glued to Sirius's temple.

Harry had never seen his father like this before, so close to the edge of his control, and it terrified him to the marrow of his bones. This was a side of Severus he'd never seen, the side of the warrior, iron hard and deadly, able to kill without blinking. But, scared as he was of this strange Snape, he also did not want his father to go to Azkaban for murdering a person, even Sirius Black. He had already lost a parent, the last thing he needed or wanted was to lose the only one he had left.

"Dad, please."

It was all he could manage to say past the huge lump in his throat.

"Stay out of this, Harry. This is between me and the bastard who killed your mother." Severus's mouth twisted and his wand began to glow.

Harry panicked then. He could see it in his mind, Severus killing Sirius, and then dementors hauling his father away to a cell in Azkaban, leaving Harry without his protection, his love, and his family. He would be sent back to the Dursleys for sure and then both of them would be in hell forever.

"Dad, no!" he shouted, then turned his wand on his father, shouting, "Expelliarmus!"

At the same time he did, so too did Lupin and Aria.

Severus was unprepared for his son or his best friend to attack him and so couldn't block in time.

The three Disarming Charms blew his wand out of his hand and sent him flying back against the wall.

He hit the wall hard, cracking his head against it and then he slid down to lie in a heap on the floor, knocked out cold by the sheer force of the spells.

Harry felt his heart skip a beat. What had he done? He had attacked his father! How could he have done that? Guilt swirled with fear surged over him in a tidal wave and he shook with the force of his emotions. He threw himself down beside his father, one hand feeling for a pulse, his wand limp next to him.

"Dad? Please, please be okay . . .I didn't mean it . . .please don't be dead!" he babbled, biting down hard on his lip to keep from sobbing like a little kid. Severus was so still . . .there was a trickle of blood running down his face . . .

Rosie whimpered and began to lick the Potion Master's face, cleaning the cut on his head with her tongue.

And Harry felt the vein in Snape's neck pulse with life.

He breathed again. ThankyouthankyouGod! He's alive! Harry nearly wept with relief, but he controlled himself.

"Harry? Is he all right?" asked Remus, concern etching his features, which were paler than usual.

"Yeah. Just . . .just knocked out cold, Uncle Moony."

"Oh my God, I just knocked out my professor!" Aria whispered, going pale beneath her tan. "I'm going to have detention until I graduate, probably."

Harry nearly smiled at that, until Sirius moved and snatched up his wand.

"Hey! Give that back!" Harry yelled, lunging at Sirius.

But the wiry man shrugged him off. "Calm down, Harry! I'm going to borrow this to prove once and for all that I'm not a traitor or a murderer. I spent eleven years in Azkaban for a crime I didn't commit." He pointed Harry's wand at Ron.

Ron yelped and tried to scramble off the bed, forgetting about his injured ankle. He crashed in a heap on the floor, half on Hermione, who blinked and awoke. She glared at Ron crossly and snapped, "What's the big idea, Ronald?"

Scabbers jumped out of Ron's hands then and started to run across the floor.

"Get him, Moony! Shut the door!" cried Sirius.

Remus slammed the door shut just as Sirius shouted the spell to reverse Scabbers to Pettigrew.

The spell shot forward and hit the rat.

Nothing happened.

Sirius was flabbergasted. "No . . .I can't believe this . . .he's an Animagus, I know he is . . .so why isn't the spell working?"

"Liar! My dad was right about you!" shouted Harry, trying to grab his wand back.

Sirius pushed him away hard. "I don't understand. The spell should have worked."

Aria sniffed, her eyes narrowed. She had never been close to Scabbers before this, never smelled his unique scent, which was that of a rat laced with an odd metallic odor that always accompanied those who were-

"Shape-slipper! He's not an Animagus! He's a shape-slipper, like me!"