Severus Snape stood, shivering, gripping a thin stick in his whitened knuckles. The wind howled around the trees of the Forbidden Forest, billowing his robe. Ahead of him, lit only by the full moon, was the Whomping Willow.
He'd seen Sirius Black do this earlier in the day, so he knew what to do; he pushed the pole past the willow's waving branches, onto a knot on the trunk. The tree froze.
With a small, twisted smile, Severus crawled down between the willow's roots, to find himself sliding into a tunnel. Curious, he crawled on.
There was an echoing cry of "Snape?"
He recognised the voice. It was Potter. Severus shook his head and crawled on; whatever secret the Marauders kept here must be good, if it distracted Potter from Quidditch...
The tunnel was rising. Ahead, there was a moan, followed by a snarl. Severus cocked an eyebrow, and continued.
Behind him, there was a thud and the sound of running. A hand yanked at Severus's shoulder.
Severus turned, to glare at the dishevelled James Potter, who was trying to pull the Slytherin backwards. Snape was about to growl a question, but was cut off by a loud, painful groan.
At the end of the tunnel, a figure threw itself down, gasping in agony; it was Remus Lupin, another Marauder. He scratched at the hair sprouting over his arms, and gnashed his teeth as they lengthened and warped. Claws sprang from his fingers, ready to tear his clothing and gouge the floor.
Severus blinked, no longer resisting Potter dragging him back down the tunnel. Lupin was a werewolf?
Potter, wincing at the effort, pulled Severus from between the roots of the willow, muttering something about how he was going to kill Sirius for this. Out of harms way, the Gryffindor leant against one of the Forbidden Forest's safer trees, gasping for breath.
Lupin is a werewolf... Severus thought, standing still and looking pale. That means...
Snape looked at Potter. "You saved my life?" His voice was a mixture of disbelief and horror. "You saved my life?"
"Yeah," said Potter, his eyes rolling under his glasses. He shook his head, and walked back towards Hogwarts, muttering "And I bet I'm gonna regret it..."
Severus turned and watched him go, too numb to use one of his repertoire of curses. Obviously, Potter's slight Quidditch skill required no exercising of the mind; he did not realise just what that meant.
Severus Snape did. He spat in frustration.
2 - Indebtedness
Lord Voldemort's power was feared by all, especially those closest to him. People thought that just because he was rich and cruel and powerful he didn't have feelings like other men, but the Death Eaters had personal experience of his hatred, rage and sadistic humour. They stood by him because they knew that fear of him would spread to them, that fear was a power in itself.
They knew that people needed the odd reminder of how much they should fear 'He-Who-Must-Not-Be-Named.' So a group of Death Eaters gathered in a hidden alley, just next to the unsuspecting village's square.
One Death Eater, Severus Snape, handed out the small obsidian bottles he had prepared. While young, his expertise in potions was respected by the Dark Lord's servants; they knew him capable of making the Umbra Solution.
Each of the Death Eaters drank the potion. It cloaked them in shadow, disguising them and making them appear more dark and terrible than a simple cloak would have done.
Clutching his wand, a Death Eater crept to the corner and peered out of the alley. Snape knew it was Wilkes, although the Umbra Solution made him unrecognisable.
Wilkes sneaked back to the others. "There're three Aurors; McKinnon, Cauldwell and Proysy. Ten other wizards."
The other Death Eaters nodded. Four prepared to Disapparate. Snape and the other two crept to the edge of the alley, where they were hidden in the shadow but had a clear view of the square; the three Aurors were standing on a makeshift podium of wooden crates in the square, trying to recruit or at least inspire courage.
Then came the signal. A Death Eater - according to their plan, Lestrange - called, "Morsmordre!"
The Dark Mark seared in the sky as the Death Eaters leapt forward, throwing the first fusillade of curses. Snape hit Cauldwell with a Morsus Hex; the Auror fell, hands rubbed at the stinging cuts now covering his body. McKinnon fell, too, as a Death Eater hit him with the Cruciatus Curse. Three wizards in the audience's front row collapsed from extreme nausea, from a widespread Egresco Spell.
The other Death Eaters Apparated around the remaining wizards. There were cries as four more fell, some to the bone-breaking Infractus Curse, others to the pounding from the Everbero Hex.
Finally, the wizards retaliated. There were cries of "Expelliarmus!", but the Death Eaters who lost their wands took spares from their robes. Proysy attempted a Body-Bind, and was answered by Avada Kedavra.
One wizard - one hit by the Egresco spell - managed to roll onto his chest. With a cry of "Casses!", a silken net flew from his wand. It smacked into a Death Eater, who fell sideways, barely missing Snape.
Snape readied his wand and aimed. "Av-"
His breath caught. The screams around him became dulled and distant.
He recognised the wizard. It was James Potter.
Of all the mudblooded, muggle-loving, wretched, weak-willed wizards, it was James Potter!
Severus could feel himself pale, and in a flash of panic he realised his body was refusing to move. His wand still pointed at Potter, who was staring at its tip as if it were a veela.
Reality smashed back into Snape's head as another wizard hit him with a burst of rope. The rope was weak, and Snape shook it off easily. He retreated, back into the alley. With a glance over his shoulder he saw Potter had collapsed, the curse induced vertigo too much for him.
The sounds of flying hexes was muffled in the alleyway. Snape sagged against a cold, stone wall, closing his eyes.
He knew why he hadn't been able to use the curse.
Potter had saved his life.
He owed Potter.
Snape pushed his fringe, now wet with sweat, out of his face, as he opened his eyes again. He had known there was a bond of sorts between him and Potter, but the knowledge had lurked at the back of his mind, forcibly hidden. He had always thought - well, hoped - that it wouldn't matter.
He looked at the Dark Mark on his arm. He remembered when it had been burnt there, a few years ago, when he'd joined the Death Eaters just after leaving Hogwarts. He had vowed to serve Lord Voldemort, to give himself to the Dark Lord.
He remembered the joy and anticipation. Death Eaters had fear, which was power, and Snape wanted power - he needed power. Ambition snarled at him and snapped at his heels, urging him on.
It was why he had been a Slytherin. Slytherins valued - no, worshipped - ambition. Nothing could get in the way of an ambitious wizard, if he used his cunning. Nothing could stop ambition: not bravery, nor loyalty, nor cleverness. It conquered them all because it transcended them all - it wasn't a virtue, it was a force. Ambition was sacrosanct.
Snape's hand became a tight fist. No bond could get in the way of serving Voldemort, because no bond could get in the way of ambition.
Severus's fist uncurled, and he buried his face in his palms. One bond could - one bond so deep and impenetrable it went beyond magic. And because of a school boy's mistake, that bond existed between him and Potter...
This was the first time he had seen Potter since leaving Hogwarts, and he didn't know or care if he had been recognised by him. It didn't matter. They'd meet again, and that bond would clash with Voldemort's orders again.
He was sure they'd meet again. Fate liked that sort of thing.
Curse Potter. Curse Black. Curse Lupin. They had thwarted his ambition, without even realising it.
Snape struggled from his thoughts, and straightened. He turned back to the alleys entrance, toward the square. The Death Eaters would have drawn out the final curses, making sure the attacked were properly terrified, but they would be finishing around now.
Snape composed himself as the other Death Eaters entered the alley; most walking, but a few dragged fallen colleagues. The umbra solution was wearing thin, and, from the dead quiet in the square, all thirteen wizards were dead or unconscious.
The Dark Mark in the air was fading as the group of Death Eaters Disapparated, ready to report back to their lord.
But Snape knew that Voldemort was no longer his lord, that he was no longer a true Death Eater. Ambition had been usurped.
3 - Repayment
Professor Snape stared morosely at the Quidditch field, carefully avoiding the sight of the jauntily enchanted banner some Gryffindor first years were flaunting. While Slytherin's record of glory in Quidditch was the source of great pleasure, Snape never really enjoyed watching the sport; it reminded him of Potter.
The late Potter.
Snape scowled. Potter hadn't been late that night; if Potter had been just a few minutes later then...
... then Snape would have been 'late'.
Severus concentrated on thinking that would have been bad. It was an effort, but practise paid off.
The echoing blast of Madam Hooch's whistle shook Snape from his thoughts, and his attention was dragged back to the players.
The blurred figures of red and green swarmed around the Quaffle. The green ones were Slytherins; they were evidently far more skilled, even to Snape's uninterested eyes. The red ones were Gryffindors; they were sustaining beginners' luck, no doubt reflective of their abilities.
One of the scarlet ones was Potter's son; presumably the one skulking above it all. In Quidditch, as in life.
The Quaffle chanced its way through a well protected hoop, thus scoring ten undeserved points for Gryffindor. Snape joined the rest of his house in a show of righteous indignation. He judiciously ignored Potter's son, who was showing off with a series of loop-the-loops.
The Slytherin team regained the ball, but a glimmer of the Snitch distracted the fickle crowd. Two players dived after it, although the Gryffindor seeker could not avoid the Slytherin captain.
Hopefully, it will teach the Potter boy not to be so cocky over his ability, thought Snape, smirking.
After their penalty, Gryffindor's fortune continued. The overtly biased attempt at commentary rambled on in the background.
Snape's gaze flicked back at the Gryffindor seeker momentarily, to find the boy was pivoting around the pitch. Admittedly, the Potter boy's ability wasn't that good, but it wasn't that bad...
Snape prided himself in being an expert in the Dark Arts, and immediately recognised the curse. Potter's son would fall, and would be lucky to end up in a countable number of pieces. Someone was using powerful black magic to control that broom, and Severus had a pretty good idea who...
But that is beside the point, whispered part of Snape's mind, ecstatically. He is Potter's son - his heir!
Ten years ago, Snape had tried to save the Potters by warning Dumbledore that the Dark Lord was after them; that hadn't worked then, but this might work now... Allowing himself a brief smile, hopefully unseen, Snape started muttering the counter-curse under his breath.
Everything except the boy became unimportant, even Slytherin scoring. Snape's eyes and mouth were itching with dryness, but he could not pause to blink or wet his tongue.
After a pause of timeless focus, the broom's gyration lessened, as did the concentration of mind and magic. As his tongue slowed, Snape could think, Potter has been repaid!
Severus's shoulders lowered, and he blinked with relief and relish. He had finally done it. How many years had he waited to be free of that accursed debt?
Maybe it was too late, maybe he could no longer find power in the Voldemort's shadow, and maybe ascending the teacher's hierarchy could slake his ambition only partially. But now he could at least loath the late Potter and his friends - such as they were - without the pain of any bond. Snape was practically glowing with happiness...
... and blue flames?
It was at this point that the professor noticed he was on fire.