For a while it seemed as though Sam and Charlie's wariness of the timeline was unfounded. Everything progressed just as it had in the books, until the night of Buckbeak's execution. "So, you want us to do nothing?" Dean asked for, perhaps, the tenth time in less than an hour. Bobby had departed after the holidays, promising to visit them for the summer as often as he could. The remaining four were gathered in Sam's room.
"Totally sure," Sam nodded. "Right about now Lupin is talking with Sirius about who got Harry's parents killed."
"And then Severus shows up and that whole drama goes down, right," Dean sighed and nodded. "I don't know man, something about just sitting here feels wrong."
"I believe I heard my name?" came the cold drawl of Severus Snape from the doorway.
Very slowly, and very unbelievingly, everyone in the room turned to look at the Potions master. "S-Severus?" Sam asked, shocked and confused.
"I do hope you know that you aren't supposed to be here," Crowley said, perhaps the only one in the room who was amused by this development. "Isn't that right, Sam?"
"Severus, aren't you supposed to be delivering Remus his Wolfsbane potion for his change tonight?" Sam asked, trying very hard to remain calm despite the rising panic he felt. A quick glance to Dean told him that his brother was engaged in a very similar internal struggle.
"It is not my responsibility to remind him of his… affliction," Severus said, his lip curling in distaste. "Sam, you of all people should understand the necessity for one to take on their own burdens and not to let others carry them."
"Enough of this," Dean muttered, drawing his wand and pointing it at Severus a moment later. "Stupify!"
Snape's look of shock could not have been more genuine as he flew backward and crashed against the wall, unconscious. "Dean!" Sam shouted, shocked. "You can't just attack another professor!"
"Look man, you said that Snape protects them from Lupin when he turns!" Dean snapped, "And if he is here now, then something is screwed here!"
"He's right, you know." Cas put in, crouching over to examine Snape. "I believe that it is called the Butterfly effect, or something to that end. You change one thing and-."
"And a whole mess of dominoes topple over," Crowley finished, drawing his wand as he knelt beside Castiel. "You two go save those three, I would very much like to avoid having to play Humpty Dumpty with Potter again. Feathers and I will deal with Severus."
"What are you going to do?" Dean asked.
"Alter his memory," Crowley said. "Unless you would prefer for him to wake up knowing you attacked him?"
"Good call," Dean nodded. He turned to his brother. "Where are they going to be?"
"Whomping Willow!" Sam said, sprinting out of the door with Dean fast on his heels.
The Winchesters tore out of the castle, nearly running over any unfortunate students who got in their way. The sun had long since set and even the orange rays of light that lingered behind were now gone. They illuminated the path before them with their wands, but their pace did not slow in the slightest.
Their run took all of about fifteen minutes, but that time seemed like an eternity. When they, finally, came over the hill that let them see the base of the Whomping Willow, their hearts caught in their throat. A large wolf-like creature was standing over five different forms and was slowly stalking them. "Get the kids!" Dean bellowed, charging directly at Lupin.
When he got close, he saw that the werewolves of this world were far different from the ones in his. The wizarding world version were the stuff of nightmares. A thin coat of wiry fur covered the beast's body, and its head was that of a wolf's. Human-like hands ended in cruel claws. It took Dean less than a moment to process all of this, but he didn't falter for a step. The werewolf, intent as it was on his prey, did not notice the hunter until Dean was ten feet away. It rapidly turned to face him, a challenging growl issuing from its chest just as Dean shoulder-tackled the beast away from the kids. The beast gave a surprised whimper and then began to snarl. In an event that was equally fortunate and unfortunate, the momentum from Dean's attack carried them over the edge of the cliff that the Willow sat upon.
Sam watched Dean and Lupin go over the cliff, dread coiling in his stomach. But there was no time for him to chase after Dean as his attention was drawn when a jet of murderous red light went soaring by him. He ripped his wand from his pocket and countered as another curse was sent at him. His aggressor was a mousy looking man with an expression full of hatred. The hand gripping the wand was missing a finger, but that did not seem to affect his ability to hold the slender piece of wood.
"Professor, watch out!" Harry shouted, pain in his voice. "His name is Peter Pettigrew, he's a murderer!"
"I know who he is, Potter," Sam called grimly, his eyes locked on Pettigrew as they began to circle. This was wrong, in the book Pettigrew had taken the first chance he could to escape. Why wasn't he doing so now? He certainly would have been able to when Remus transformed. "Tell me, are you four okay?"
"Ron can't move, his leg is badly injured!" Hermione said, her voice far more controlled than Harry's had been. "Sirius Black, he's bleeding a lot!"
"Alright, Granger, stay calm," Sam said, breathing a quiet sigh of relief. "You just stay there, I will take care of this."
"Ah, a professor are we?" Pettigrew sneered, "After I finish you I will kill them. Imagine how the Dark Lord will reward me when I bring him news that Harry Potter is dead! Perhaps I will bring him his head as proof."
"You won't touch them," Sam promised, his voice cold.
Their duel started then. Sam had, in preparation of the battles that inevitable awaited them, practiced dueling with Dean extensively. But the difference in their duels and this were immediately apparent. Jets of light were blistering hot when he dodged them, and Pettigrew was nothing like he had thought. The mousy man was desperate; firing spell after spell with hardly a pause to catch his breath. Killing Curses went soaring wildly about the clearing they dueled in. The students gave shouts of surprise and fear when one such Curse hit the ground near them and caused a small crater to be blasted in the ground.
Perhaps it was their screams of fear, but Pettigrew's eyes lit up and Sam had to dive in front of them whilst simultaneously casting a Shield Charm to stop the spell that Pettigrew sent at them. On his feet at once he fended off curse after curse, unable to back up even a single step as Pettigrew advanced on them, a manic gleam in his eye. "Run!" Sam ordered, managing to send his own curse flying back at Pettigrew. "Get out of here, now! You are only in the way!"
"We can't!" Harry said, crouching protectively over the body of a large black dog that Sam assumed was Sirius. "I won't leave him!"
"Dammit!" Sam said, fending off yet another curse. The ground beneath his feet was hot from the heat of the magic, and his adrenaline was racing. "Leave the kids alone!"
"The Dark Lord will surely reward me greatly for this!" Pettigrew said eagerly, pausing just long enough to speak. "Now, die!"
A sudden growl ripped from behind Sam, but he couldn't turn around as Pettigrew had started their duel anew. But, an instant later, a large mass of black fur rushed by him and made a beeline for Pettigrew. Clearly not expecting this, the mousy man was an instant too slow in getting a defensive curse off. The large black dog leapt into the air and its jaws locked around Pettigrew's throat, its weight forcing Peter to the ground. For just a moment a horrible scream came from the beneath the dog's feet, but then it was silenced when the dog made a sudden shake of its head.
Pettigrew was silent and, Sam suspected, he would be silent forever more. Sirius, as that was who the black dog was, slumped over and fell onto his side and released Pettigrew's throat. Sam, cautiously, began to walk forward, his wand aimed directly at the still body of the man who had caused the death of Harry's parents. As he expected, his throat was torn open and he was trying desperately to draw in air. Fear was in his eyes and Sam looked down at him. He opened his mouth to speak, perhaps to beg for mercy or for assistance, but nothing came out. Sam stood over the small man and did nothing. He watched Pettigrew choke to death on his own blood, a smell sense of satisfaction as the man who caused so much pain and suffering died in such a fashion.
Once the light had faded from Pettigrew's eyes, Sam leaned down and pulled away his wand. He stowed it in his back pocket and turned his attention to the unconscious form of Sirius's Animagus form. One Levitation charm later and the black dog was bobbing in the air before him. "Are you three alright?" Sam asked, kneeling before them.
"Professor, that was bloody brilliant," Ron said, though his face was white as a sheet. Sam had to take only one look at his leg to know that walking was not going to be possible for the Weasley. "Come on, we need to get that leg taken care of in the hospital wing."
"Professor, what about your brother?" Harry asked, looking back to the spot where Dean had gone off the cliff with the werewolf. "Shouldn't you go after him?"
"Dean will be fine," Sam said, secretly wishing he could do just that. But he needed to make sure these three were looked after as Snape couldn't. "You three need to get to the Hospital Wing."
Sam had just begun to wrap Ron's leg with a strip of fabric he had ripped from his own robes when Harry spoke up again. "Professor, is it… does it feel a lot colder now than it did a few minutes ago?"
Slowly, very slowly, Sam let out a long breath. When he had left the castle he had not been able to see his breath even slightly. Yet, now, he could clearly see it. In fact, the temperature seemed to be dropping by the second. He looked up and, to his horror, he saw hundreds of dark robed figures descending upon them in the night sky.