A/N: This was supposed to just be a drabble from my Tumblr Drabble Prompt Game.
It has not panned out that way.
"Oh dear Merlin, what is happening?" Hermione Granger clutched at her curls and stared wide-eyed at the being before her.
"Hysteria is unwarranted, Miss Granger," Severus Snape drawled in reply, eyeing her like she was the stupidest girl to ever live.
Hermione gasped, the sound of his voice slithering across her psyche like a snake in a sleeping-bag and making the hair on the back of her neck stand on end.
"I thought you were dead!" she gasped, subconsciously reaching toward him and touching his chest to confirm he was, in fact, real and not simply an apparition conjured from the depths of her potentially demented mind.
"You were mistaken," he replied coolly. "And while I'm sure it must be a disappointment for you, do try and get of a hold of yourself and get out of the doorway."
He stepped closer, crossing the threshold and invading her home as though he had every right. Indeed, he put his hands on her shoulders and steered her pliant form out of his path and into the wall, pinning her just inside the doorway before he glared down at her.
"You're alive," Hermione repeated, shell-shocked.
"I'm alive," he sneered. "Though why you feign surprise when it's by your hand, I cannot fathom."
"My... my hand?" Hermione asked, staring up at him in confusion and sensing that he wasn't overly thrilled by his continued existence, actually.
"Your hand," he agreed. "It was you who forced the bezoar down my throat, you may recall. You who fed me some experimental antivenin for Nagini's venom. You who injected Blood Replenishment potions into my veins. You who sealed my wounds with some spell that baffled the Healers at the hospital when the same wounds were a nightmare for them when treating Arthur Weasley for the same ailment. You who cast innumerable charms over my dying form and thus, rendered me back into existence on this wretched plane."
"You... oh, god! You survived. You..." Hermione stammered, her mind trying to catch up with what he was telling her, trying to fathom that this wasn't some crazy dream.
"Indeed," Snape hissed. "And I ought to inform you, Miss Granger, I'm not here out of gratitude."
Hermione's stomach flipped with fear when he glared down at her like that before he kicked the door to her flat closed, letting it slam sinisterly.
"Sir, I..." she began, frowning up at him.
"Do you have any idea what you did, you wretched little fool?" he snarled, baring those crooked teeth at her and glaring down that hooked nose at her hatefully.
"What are you... sir, I don't understand," Hermione tried.
The breath huffed from her lungs when he pulled her forward only to slam her back against the wall viciously, and it was only then that she realised he was trembling with fury.
"You moronic, idiotic, short-sighted, stupid witch!" he snarled into her face. "How could you?"
"I... sir, what?" Hermione asked, though it was difficult to enunciate clearly when he began shaking her violently.
"What did you think the Relligo Spiritus charm did, you fool!?" he spat.
"Um..." Hermione wracked her brain, though with him still shaking her and rattling her brain like that, the thought didn't come easily.
She gasped when she unearthed within her psyche the spell he spoke of, her eyes flying to his furious face.
"Oh... my..." Hermione breathed when he flung her back against the wall once more, realising she knew why he'd come; knew how he'd survived when even her healing efforts ought not to have saved him from his well-earned oblivion.
"Tethered Souls," he snarled in her face, looming over her threateningly. "You tethered our fucking souls, Granger!"
Hermione gulped audibly in the silence that followed but for his heavy breathing while he glowered at her.
"Well..." Hermione murmured; her eyes fixed upon his face while a rushing sound began to fill her ears. "Shit!"