gingertart50 prompted me with Severus, Minerva and Filius (and Pomona too if I can sneak her in?): Friendship, Heads-of-House-meeting, alcohol.
An Historic Occasion (G; Severus, Minerva, Filius, Pomona, Albus; 300 words): Severus receives an unexpected honour.
Tap! Tap! Tap!
Severus looked at the clock on the mantle of his study; it was only six o'clock in the morning, but he knew better than to ignore the brisk tattoo that had sounded upon his door. What could she want? he wondered, opening the door to reveal Professors McGonagall, Flitwick, and Sprout. "Good morning?"
McGonagall smiled. "You don't sound certain, but we are."
"We come in friendship to invite you to an early breakfast, Professor Snape," said Flitwick.
"That's right, Severus, dear. It's a tradition," Pomona told him.
Severus relaxed. He'd always been on good terms with Pomona, with whom he shared an interest in botany. I'm not in trouble, then, he thought, following the others.
They led him to the courtyard that was reserved for the Heads of House, where he found Professor Dumbledore waiting for them.
"Good morning, Severus!" he greeted him cheerfully. "Sit down, sit down! I have excellent news."
"Where's Professor Slughorn?"
"Better yet," said Flitwick, "where are the mimosas?"
Albus chuckled and sent a pitcher levitating towards him. "To Ravenclaw," he toasted, once they'd all filled their glasses.
Severus drank as toasts were made to Hufflepuff and Gryffindor.
"And also, to Slytherin," Dumbledore toasted, "on this historic day!"
"To Slytherin," Severus said, thinking, He can't possibly mean to-
"I think, perhaps, you're beginning to understand?" McGonagall asked.
Severus looked to Pomona.
"That's right, dear," she said, grinning.
"To Hogwarts' youngest ever Head of House, Professor Severus Snape!" everyone toasted.
Severus blushed and drank, warmed more by the others' smiling upon him than by the champagne in his drink-or even the honour that had just been conferred upon him. "I . . . don't know what to say. I never expected-"
"Your modesty does you credit, Severus," Pomona interrupted him, "but Slytherin's never been in better hands!"