Severus Snape shot out of Greenhouse Three as soon as class dismissed, ready to get out of the bitter December sleet and into his favourite armchair by the fireplace in the Slytherin common room. He had already finished this week's monstrous amount of homework, except the new Herbology essay the fifth-years had just been assigned. Severus was looking forward to taking a break; later he thought he might try to come up with a few new hexes. He had been writing them in one of his mother's old Potions books; when he wasn't inventing hexes and jinxes he was delving into Eileen Snape's N.E.W.T.-level textbooks, particularly Defence Against the Dark Arts and Potions, making notes and correcting the instructions where needed.
As he trudged across the vast vegetable patch (destroying Hagrid's cabbages with a vengeance more than any flesh-eating slugs ever could – why they were called flesh-eating slugs when they ate cabbages, he'd never figured out), he thought about his grandmother, Eleanor Prince, who had taught him everything she knew about herbs and potions the summer before she died, almost two years ago now. She had been a brilliant potioneer, and his only family member that he had ever felt somewhat close to.
His reminiscing interrupted, he quickly dropped his tattered bookbag, simultaneously drawing his wand. There were only two people in this wretched world who called him that.
And sure enough, Severus, whirling around, saw James Potter and Sirius Black standing ten feet away, wands withdrawn and pointed at him.
"Impedimenta!" Snape snarled.
But he wasn't quick enough; not a second later his wand had flown out of his hand, landing some fifteen feet to the side.
"What's Snivellus got in his bag, eh? Petrificus Totalus!" Potter cried as Severus went after his wand. The growing crowd of onlookers laughed loudly.
Unable to move, the snow and wet slush soaking through his secondhand cloak and robes, Snape watched furiously as Potter and Black kicked open his shabby knapsack and began to sift through his textbooks and carefully organised notes.
"Ah, Snivelly got another Outstanding on the last Defence essay… say, d'you frame them and hang them by your bed?" Black sniggered, throwing the scroll of parchment (which was rather thick for an essay) into the snow.
"Well, at any rate, I doubt he needs these notes anymore, seeing as how he already knows the Dark Arts by heart, surely he can defend himself against them -" Snape struggled fruitlessly against the curse as Potter let his notes go flying away into the cruel breeze.
"And look, here's some homework -" Black let another sheaf of parchment go flying.
"What's this?" Potter had picked up Advanced Potion-Making, which had been lying open upon the slushy snow. "Already working ahead, Snivelly? Think you're bright enough to know better than ol' Libatius Borage, eh? And what's this… Levicorpus… making up new spells? Well, let's see what it does." After studying the old textbook for a moment, Potter flicked his wand upward silently.
Though he had known what was coming, nothing could have prepared him to be flung upside down instantly in a flash of light.
"Ha!" Potter cried, laughing hysterically along with Black and the now large group of onlookers, who seemed rather content to stay out in the sleet and watch the antics of the brilliant James Potter and the handsome Sirius Black as they messed around with that odd Severus Snape. "Well, Snivellus, I guess I'll just borrow this book for a while, I'm sure you have more hexes for me to use – and I sure appreciate the advance help for ol' Sluggy's N.E.W.T. class!" He picked up Advanced Potion-Making once again, and after making sure Severus's remaining books were scattered across the snowy ground, Potter flicked his wand downward, sending Snape down face first into the slush.
Potter, Black, and their entourage of admirers had vanished over the hill before Severus lifted himself out of the snow. Shaking with fury and the freezing cold, he retrieved his wand and began to collect and dry his possessions.
"It was Potter again, wasn't it?"
Startled, Snape spun around, wand at the ready. It was Lily Evans, accompanied by her plump friend, Alice, or whatever her name was. Both were holding lengths of wet parchment. Evans's bright green eyes were narrowed in suspicion, anger, and concern.
Severus did not answer; he was shaking so badly that he couldn't have if had wanted to.
"I knew something was wrong when I saw that crowd of people," Evans was saying fretfully. "I would've been here sooner, but I stopped to talk to Hagrid -"
"I don't need your help," Severus ground out.
"Well, anyway, Potter and Black both need strong Shrinking Charms for their egos. Here's your stuff." Shoving the wet parchment into his hand, Evans adjusted her scarf and followed her friend to the castle.
I don't need their help, Severus thought furiously as he summoned the rest of his notes. I can take care of myself. I'll get them back. After all, he was the Half-Blood Prince.
A/N: My beta reader, Jamc91, has informed me that James and Sirius would never be quite this cruel - but how else would they have found Snape's curses?