The Full-Moon Prince, a harry potter fanfic

This work was inspired by seventeen moons by we-built-the-shadows-here.

Chapter 1: Prod the Knot

Sirius I

Thursday, 18 December 1975

Of all the plans Sirius had devised, he had to admit he'd outdone himself this time.

Snivellus had been snooping around, sticking his abnormally large nose where it didn't belong, and he was currently on Moony's trail. Apparently, the git had followed Moony and Madam Pomfrey to the secret tunnel beneath the Whomping Willow, only to find that Madam Pomfrey had returned without the Gryffindor prefect. Sirius knew that the creep was already starting to suspect them, and it had been a bit fun to watch him be on-edge. But following Moony was a step too bloody far, which is why Sirius decided it would be best to corner him and put him back in his place.

What Sirius hadn't expected was for Snivellus to stand up to him and ask him pointedly about what Moony was doing under the tree. He had been one second away from hexing the git on the spot, but a single image flashed before his eyes, and he knew he could do something even better.

"Why don't you find out for yourself? Just prod the knot, and you'll put the tree to sleep. Unless you're too much of a coward."

Sirius lied down on his bed as he reminisced about how Snivellus grew flustered and walked off. Sirius was too amused to even hex him from behind; he wanted to see what would happen. Of course, another thought crossed his mind; if Snivellus died, Evans would be devastated. However, if James swooped in and saved Snivellus, it'd kill three birds with one stone; Moony would be grateful that James saved him from killing someone, Lily would be grateful that James saved her 'best friend', and Snivellus would hate every second of it.

When Sirius had told James about the plan, he was almost certain the latter would see how brilliant it was.

"You what?!" James's eyes went wide as Sirius finished explaining.

"Look mate," Sirius said, "all you have to do is follow him in and pull him away at the last second."

"What if he gets killed?! Dumbledore would know who was involved!"

"You're not hearing me. Pull him away at the last second; just make sure he's not too close to the shack, yeah?"

James seemed hesitant at first, but the concern soon vanished on his face, replaced by a grin. "Lily'd think I was a hero..."

"Now you're getting it," Sirius said. "Never thought it'd take you thinking with both your heads to see how this could work out."

James smacked Sirius with a laugh and grabbed his cloak from the dresser. He was having another one of his fits of excitement, his breathing starting to quicken and his hands shaking a bit. "I'll give you details when I get back."

Sirius let out a sigh as he checked the grandfather clock in their room, the silence only broken by Wormtail's snoring. It wasn't too late, but late enough that a certain snake would be slithering through the grass to the Whomping Willow, and eventually down the tunnel to the Shrieking Shack. If all went well, James would be a hero. And Sirius knew that all would be well.

James I

"Ta," Sirius said with a grin.

James flung the cloak over himself and disappeared into thin air as he stepped out of the dorm room and took the Marauder's Map out of his pocket. He whispered, "I solemnly swear that I am up to no good," and tapped his wand on the parchment. Soon, the map came to life, and he found himself searching for Snivellus's name. Sure enough, the Slytherin boy had just left his common room and was currently making his way down the corridor.

James hurried out of the common room and swiftly made his way down the corridor to the stairs leading down, his chest flooding with sheer, unadulterated excitement. With each step downward, the sensation grew, and thoughts about the aftermath made him feel drunk; he could imagine Lily's almond-shaped eyes gazing at him after hearing of his actions, and he even imagined her putting Snivellus in his place for objecting to it. Another little thing to wedge between the two so he could slide right in.

As James reached the ground floor, he checked the map again and saw that Snivellus had just reached the edge of the map's range; he and the lads hadn't properly mapped out the area around the Whomping Willow yet, but they were planning to once they started their plans of becoming Animagi after Christmas hols. Slipping out into the alcove, which he knew led out to the Whomping Willow, he kept his eye out for any names that may approach; the closest one was Filch, but the squib was in bed.

Sure enough, James arrived just outside the castle's threshold, staring out at the Whomping Willow. The usually animated tree was perfectly still, a sign that Snivellus must have prodded the knot. James took a deep breath, letting the cold, near-winter air fill his lungs, before hurrying to the tree. After tonight, everything would turn around for him and Lily. After tonight, he knew all would be well.

Severus I

The tunnel beneath the Whomping Willow was smaller than Severus had expected when he first entered, albeit not by much; while it didn't bother him, what really confused him was how the taller Lupin managed to make the trip to wherever this tunnel led before transforming (assuming his theory was correct). At first, he'd been cautious about what Black had told him, but in the moments after learning how to sedate the hostile tree, he'd considered why the bastard would even tell him this.

It could have been that Black wanted Severus to try, knowing that it wouldn't work, and then watch him get killed. Or it could have been that it actually did work, and Black expected Severus not to go for it, whether or not there was some dark secret waiting for him. Or it could have even been that Black genuinely wanted Severus to go in and find out but for the purpose of having a ravenous werewolf silence him for good. Or perhaps, Black didn't want Severus to go in, but told him anyway, believing that the latter would overthink the information and place himself in a perpetual cycle of figuring out whether it was an odd- or even-numbered bluff.

But if there was even a small chance of finding evidence to get Potter and his gang expelled, Severus would take it. And based on the haunting howls and snarls coming from the very end, he knew his hunch had to be right.

The deeper Severus stumbled his way down the tunnel, the more he had the feeling that someone was following him. Despite being unable to see, he didn't dare draw his wand and light the way; not only would the Trace alert the Ministry of his location, which could result in him getting in trouble, but in the event there was a bloodthirsty monster somewhere down here, it would alert it to his location. And even if the ceiling wasn't as low as it was, he knew he couldn't outrun a werewolf.

After what seemed like an hour of walking, Severus saw a light at the end of the pitch-black tunnel, albeit a faint one, and his stomach twisted. He had the feeling that this was the end destination, where Lupin probably was, and he was starting to wonder where the tunnel had brought him. Being underground had distorted his sense of direction; for all he knew, he could be in Hogsmeade. His feet started to slow the closer he got to the light source, and he was eventually able to tell that it was coming from some sort of gap. He was only a few steps away when he saw that there was a crate covering a hole leading to what he assumed was some sort of building, and, carefully and quietly leaning forward, he glimpsed through the gap.

Severus saw that the tunnel had led to the inside of some sort of building, as he had predicted, but he couldn't see too much other than the moonlight peeping in from a gap in the boarded-up window and the silhouettes of some sort of canine. Although the shadow wasn't too clear, it was clear enough; the beast's snout was short, and its tail was tufted. It was a werewolf.

A hand suddenly grabbed Severus from behind and pulled him back, and Severus spun, drawing his wand on whoever had touched him. "Who's there?!" he hissed.

Another hand suddenly appeared and grabbed his wrist, and Severus started kicking wildly, resulting in coming into contact with something solid and a low grunt. A large weight, similar to that of someone his own age, if not heavier, barreled into him, knocking the air out of his lungs, but he managed to snake his hands free and grab at his attacker. He felt the sensation of some sort of cloth and pulled hard, and as it fell to the ground, he saw the moonlight glean off of a familiar pair of glasses, which were worn by a familar face.

"Potter?!" Severus hissed, now enraged.

"Thought you could poke your nose into our business?!" Potter hissed back. "Come on; you'll get yourself killed."

Severus could see the excitement on Potter's face, and his blood turned cold. The other boy was enjoying this! "Get the fuck off me!" Severus tried pulling away and shoved Potter back, but the other boy grabbed his arm.

"We're going back to the castle," Potter growled, yanking hard.

"I said GET OFF!" Severus swung his free hand and struck Potter in the face, knocking the boy back and causing him to release his hold of Severus's arm. This, however, caused Severus to stumble back in kind, and his back hit the crate, which caused it to move slightly and widen the gap.

The tunnel was now illuminated by moonlight, and Severus felt his blood run cold as he realized where he was; half of his body was still in the tunnel, but the other half was inside the room. The same room with the werewolf in it. The same werewolf that had stopped howling and snarling, and was now looking at Severus with its unsettlingly human eyes.

Severus let out a yelp as he crawled back, deeper into the tunnel, and the yelp transformed into a scream as the werewolf bolted towards him, its mouth opening to reveal its sharp fangs. He attempted to raise his wand to push it away from him, but it was too late; the monster had latched itself onto Severus's other arm, the teeth digging in deep and painfully, and there was a rough pulling sensation as it tried dragging him back into the room.

"MOONY, NO!" Potter charged head-first at the werewolf, the fool not having drawn his wand, and started pulling the monster back by its neck. "THIS ISN'T YOU!"

The werewolf immediately released its hold of Severus and turned, throwing the Gryffindor boy back against the wall of the tunnel. Severus tried to stand, but he made the mistake of using his damaged arm to brace himself; he soon found himself face down on the ground, the realization that he wasn't already running away causing him to panic. As he fought the fear and made himself stand, he heard a blood-curdling screaming and choking sound from behind. Too fearful for his own life, Severus stumbled down the tunnel and away from the room and the werewolf, his heavy breathing coming out in desperate sobs.

Severus's foot caught a root, and he fell forward and onto his stomach once more, the fear taking hold again as he realized the sounds of fighting had stopped. He scrambled to his feet and whimpered out, "Lumos!", holding the light down to the ground so he would avoid tripping once more. There was the sound of rapid steps from behind, and before he could turn, he felt long teeth sink into his leg.

Severus screamed, sobbing as the werewolf started thrashing him against the ground and walls of the tunnel. In a panic, he swept his wand at the beast and cried out, "Sectumsempra!"

The werewolf yelped as a gash appeared along the side of its head, one of its ears coming undone and sliding off its head. Its rage seemed to grow as it released Severus's leg and went for his wand arm instead.

"Langlock!"

The werewolf's tongue immediately shot up and stuck to the roof of its mouth, causing it to thrash around by itself as though to shake out whatever had caused it.

"Levicorpus!" Severus watched as the beast was forced off the ground and reduced to hanging upside down, its feet now on the ceiling. He struggled to stand, but he found enough strength in one leg to support himself, although he knew he wouldn't last for long. He started staggering back, keeping his wand on the werewolf with each step.

To his horror, the monster had dug its claws into the ceiling, and it was now starting to pull itself closer to Severus.

"Unguisaugeo!"

The werewolf's claws started growing at an uncontrollable rate, becoming rooted in the dirt above and trapping it in place. It began to roar and fight manically, pulling itself free of the ceiling and causing it and some of the ceiling to come down, resulting in a cloud of dirt that blinded Severus.

Severus wiped his eyes, thankful for the moisture already present to catch the dirt, only to find that the light from his wand was now bouncing off the particles in the air, causing him to lose track of where the exit was. Before he could turn and figure out where the walls were, a shape bolted toward him and once more knocked him to the ground. The werewolf, bloodied and dirtied, its claws a mangled mess, buried its muzzle into his stomach, and he screamed as he felt the flesh being torn off of him.

Severus screamed, "Sectumsempra!", and another gash appeared on the monster's exposed neck and shoulder, causing it to release its hold. It had to end. "Sectumsempra! Sectumsempra! Sectumsempra!"

Wound after wound appeared on the werewolf's body, and the beast started staggering back. Severus was shaking, the fear within him overwhelming his urge to turn and run; he had to end it. He had to end it.

"Sectumsempra! Sectumsempra! Sectumsempra!"

Severus was on his knees, staggering backward and back onto his feet before advancing, his arm swinging wildly and near-limply as his casting grew more and more wordless. The werewolf's movements had started to slow, and a dark, copper-scented pool was forming beneath it as it tried retreating down the tunnel. Eventually, once he was too unsteady to move his wand through the air, the beast collapsed, its form going deathly still.

Severus's breathing was slow and shallow, coming out in an unsettling whine as he turned and limped his way back from where he had come, back toward the entrance beneath the Whomping Willow. He could feel his throat tightening with each step. His shirt and trousers were wet and sticky with blood, and each movement he made reminded him of the wounds responsible for it. The weight of what had happened started weighing him down, until he finally collapsed and broke down, realizing he was going to die, alone and in the dark.

"... help..." Severus whimpered as he felt the strength leave his limbs, causing him to fall to the dirt ground on his stomach. "... Lily..."

The world darkened around him, but in his last moments, before everything went black, a light appeared at the end of the tunnel. This was it. After tonight, he would be at peace, his soul taken wherever it was that ghosts were denied.

In the end... after tonight... all would be well...