"Severus?"
"Good evening, Petunia."
Glancing between Aunt Petunia and Professor Snape, Harry Potter felt his entire worldview collapse.
One was easily the relative he despised most on Privet Drive, and the other was without question his most hated teacher at Hogwarts. Having the two of them standing together like this—his double dose of dislike—was almost too much to handle.
But wait... why did they even know each other?
Harry prided himself on understanding Aunt Petunia fairly well. She was, without doubt, the most magic-hating Muggle he had ever met. He could still remember the look on her face, years ago in that seaside hut, when she'd spoken of his mother...
And Professor Snape? The Head of Slytherin House—a man whose house was notorious for its disdain toward Muggles and Muggle-borns.
Yet here they were, calling each other by their first names, as if they'd known each other for years. The whole thing was beyond bizarre.
...
"Dudley, Dudley! What's wrong?" Uncle Vernon's shrill voice shattered the uneasy silence.
The large man waddled in from the living room, his walrus-like mustache quivering wildly, as it always did when he was agitated.
Harry shot a wary glance at Dudley and instinctively stepped aside. His cousin swayed on the spot, his face turning greenish... then opened his mouth and vomited all over the doormat.
"What on earth is going on here?" Uncle Vernon roared.
"Dudley…" Aunt Petunia snapped out of her daze. She cast a quick, nervous glance at Professor Snape. "This is my son..."
Snape's cold eyes swept over Dudley Dursley's rather "sturdy" frame.
He raised his wand toward the floor. "Scourgify."
The mess vanished instantly.
Uncle Vernon's eyes snapped toward the unfamiliar man, his face darkening.
"And who are you supposed to be?" he demanded harshly.
"Severus Snape," came the icy reply. "Potter's Potions teacher."
"Potions? What the devil is that supposed to be?" Vernon muttered under his breath. But when his eyes landed on the wand in Snape's hand, he shut his mouth instantly.
A year ago, an unfortunate run-in with Arthur Weasley had already taught him to tread carefully around wizards.
Harry also noticed that Snape's wand now had a sleek case wrapped around it—something new—but quickly pushed the thought aside.
...
Together, they helped a trembling Dudley over the threshold and onto the sofa.
"Severus, this is my husband," Aunt Petunia said, her tone wavering as if it took all her courage to speak.
Harry would have bet anything that Uncle Vernon was every bit as shocked.
"Petunia... you…" He pointed from his wife to the greasy-haired wizard standing before them.
"He was my neighbor when I was little... mine and Li—mine and my sister's," Aunt Petunia added quietly.
Harry heard every word.
What? Snape had been neighbors with Aunt Petunia—and his mother?
Why had no one ever told him? Not Lupin, not Sirius, not even Dumbledore...
Harry's face froze in stunned disbelief.
"He's ill, Petunia!" Uncle Vernon said, not noticing the tension. His attention was on his son. "Who did this, son? Tell us their names—we'll catch them, don't you worry."
"It was... him..." Dudley stammered, pointing a trembling finger at Harry.
"Come here, boy!" Uncle Vernon barked, glaring furiously. "What did you do to my son?"
"Vernon—"
"Mr. Dursley—"
The two voices overlapped—Aunt Petunia's and Professor Snape's.
They exchanged a brief look before Snape stepped forward, positioning himself between Harry and Uncle Vernon.
"It was done by a Dementor," Snape said calmly.
"A what?" Vernon muttered, frowning.
"They're the guards of Azkaban..."
To Harry's shock, it was Aunt Petunia who'd spoken. Aunt Petunia knew about Dementors?
Her words hung in the air for two long seconds before she clapped a hand over her mouth, as if she'd accidentally blurted out something indecent.
Harry's mind reeled. As if today hadn't already been full of impossible things, a Dementor on Privet Drive now seemed almost ordinary by comparison.
"Correct," Snape confirmed, nodding. Then he drew a small vial containing a faint red liquid from his pocket.
"What's that?" Uncle Vernon bellowed. "You're not poisoning my son, are you?"
Snape shot him a withering glare.
"You're not feeding my boy that stuff!" Vernon continued to rage. Clearly, Dudley still carried the trauma of magical mishaps—like the time he'd eaten the Weasley twins' candy and grown a tongue over a meter long.
"Vernon!" Aunt Petunia grabbed her husband's arm, holding him back before he could lunge at Snape.
Meanwhile, Snape leaned over Dudley, pouring the potion carefully between his lips.
"Cheering Potion," Snape said evenly. "It helps counteract the aftereffects of a Dementor's attack."
Dudley coughed violently, then pushed himself upright with effort.
"I think I'm okay now, Dad," he said weakly.
...
Uncle Vernon guided Dudley upstairs to rest.
Down in the living room, only three people remained.
Harry sat uneasily on the sofa, certain Snape wasn't here to say anything kind about him.
Yet neither Snape nor Aunt Petunia spared him even a glance.
"You're teaching at Hogwarts?" Aunt Petunia asked, her voice trembling slightly.
"Yes," Snape replied with a curt nod. "Potions."
"I remember... that was her favorite subject," Aunt Petunia said before quickly covering her mouth again.
Harry felt dizzy. Too much had happened today for his brain to keep up.
"I believe I'll be taking my leave," Snape said suddenly, rising to his feet.
He took Harry firmly by the sleeve and steered him toward the front door of Number Four, Privet Drive.
"Potter," Snape said sharply, his words clipped and venomous. "You are not to tell anyone what happened today."
"Anyone."
Before Harry could even respond, Snape vanished into the darkness.