Severus spent six hours confirming that it hadn't been a golem or some other form of trickery, and that none of what remained was cursed or otherwise designed to cause him harm. Remarkably, there was no DNA residue, no stray hairs on the robes (and the witch, from the brief glimpse he'd had of her, had had a lot of hair). Nothing.
He examined the robes, the elastic hair tie, the leather cuff-style bracelet, the worn canvas purse that had been charmed to be more durable than it should have been. There was a small, simple glass bottle sealed with wax in the inside pocket of the robes; it contained a silvery strand of memory, and was labeled 'PARADOX' in his own hand.
Severus owled Dumbledore to request the use of his Pensieve, and set the memory aside. While he waited for the headmaster's response, he emptied the bag across the dining room table and examined the things that it had contained.
A cotton shift nightgown with a bra and two pairs of plain white knickers rolled up inside of it. A black button-down shirt. A hairbrush. A small tub of vanilla-scented hair cream. A zipper bag with a roll of gauze, six vials containing standard healing potions, a bezoar, and a tube of antiseptic paste. Three pairs of socks rolled into neat balls. A battered, dog-eared, water-damaged copy of Dune, its binding held together by Spell-o Tape.
The items weren't particularly interesting in and of themselves. The clothes looked about the right size to belong to the witch who had vanished. The personal items and first aid kit hadn't been spelled or otherwise supplemented. It might as well have been an overnight bag for a particularly light packer.
The clothes she'd been wearing were more intriguing. The robe was wool, reinforced with the same spells he habitually cast on his teaching robes to protect against potions-related incidents, and very plain. It was a washed-out gray color that might actually have been black a decade or two before. Her boots were leather, worn and scuffed and faded but spelled and reinforced exactly the way he protected the boots he wore when he taught. The wool trousers and button-down shirt were also old and well cared-for, the colors faded (the trousers had probably started gray, and the shirt coppery red, maybe orange) but hardly going threadbare.
It was odd that she hadn't had a wand with her at all.
More odd was the vial of memory with his handwriting on the label. Luckily, he'd only just finished going over the robe a third time for missed secret pockets or items sewn into seams when the Pensieve arrived in a burst of phoenix flame.
After casting a few more detecting charms, he placed the memory into the stone basin and watched it swirl.
"Well," he said to himself, then he lowered his face into the basin.
The memory took place in what could only be described as an opulent potions laboratory. It was the sort of place he'd planned out for himself when he'd been an apprentice, dreaming of the full range of his own potential. The counters were exactly the right height, the shelving endless, the cauldrons gleaming in every useful variation from standard pewter to specialized silver. There were knives of all sorts, a center-island with a wooden countertop glossy with non-reactive resin. And the attached ingredients store room was almost as large as the laboratory.
He was immediately jealous of the man in the memory. He was tall and thin, long silver-white hair drawn back into a tail and glossy with Standard Potioneers' Grease to keep stray strands from ruining a brew. His robes were as opulent as the room, charcoal cloth swirling with Slytherin-green embroidery over an immaculate Potion Master's frock coat. Polished dragonhide boots.
The man, the Potions Master, worked deftly. There were three cauldrons in use. Timing spells glowed faintly above two of the cauldrons, one simmering and the other cooling. The Potions Master stirred the third cauldron with even turns of his wrist, the thick glass stirring rod sweeping around in a figure-eight.
"Set," the witch from Severus's sitting room said, walking out of the ingredients room. She carried a tray of assorted ingredients, already prepared for the Master's use.
The Master said nothing, but withdrew the stirring rod and picked up the first ingredient on the tray. The witch moved to the first cauldron, picking up a fresh stirring rod (this one a thin copper rod with a crook in the end) and stirring slowly counter-clockwise.
They worked in near silence. The Master's potion quickly reduced to a crusty paste that frothed like vinegar and baking soda when the witch's potion was added. Then came a rush of adding ingredients, stirring, adjusting heat, changing cauldrons, and, eventually, pouring the final potion into a goblet that had been kept chilled like a salad plate.
The two stared at the goblet. It sat there, a thin waft of white steam curling up from the potion. Severus moved closer to see that the potion itself was a vivid blue and smelled a bit like overcooked turnips.
"Are you ready?" the Master asked, and Severus's head jerked around to take a second look at the man. It was him. Himself. Severus Snape.
But it wasn't him. It couldn't be him. The wizard in the memory was old. Very old. His hair was silver instead of black, going to white at the temples. His face was deeply wrinkled, especially the parenthesis lines around his mouth. His hands were almost translucent, the veins showing blue through his skin.
He was unstooped, his movement still sure. He had to be at least eighty years old, though. Perhaps more. Surely not one hundred.
Severus turned to the witch, looking at her more closely. His other, older self was watching her as she went through the things he'd just spread across the dining table. Her clothes were at the bottom, cushioning the first aid kit. The cover of the book caught on the edge of the bag as she put it in and tore, and the old Severus patiently took it from her and repaired it with more Spell-o Tape. The hairbrush had a few strands of hair stuck in the bristles.
He couldn't place her at first, but it was the hair that was telling. It was a mass of unruly curls, strands frizzing around her face despite the ponytail. The robes might have been tailored for somebody else, or perhaps had been tailored for her before the lean times, and she was certainly experiencing lean times. She was skeletally thin, almost frail-looking. She was average height, could have been pretty if she wasn't so malnourished. She had hazel eyes, piercing and intelligent in bruised sockets.
Mostly, she was a very average-looking witch. Her robes were nondescript. Too big for her, and with no particular decoration. He couldn't guess her age other than that she wasn't particularly young or particularly old.
But the hair. Curls everywhere, the frizz growing more pronounced the longer she worked on their potion. He'd watched that exact hair do the same thing over the course of Potions lessons for the past two years.
Hermione Granger. A middle-aged Hermione Granger fallen on rough times.
In the memory, Granger put her bag over her shoulder and smiled at the old man that he was still having a hard time reconciling to be himself.
"Well?" she asked, almost cheeky. She was holding the glass jar he'd found the memory in. "Do you have anything you want to tell yourself?"
He scowled at her, though there was no heat in the expression. The memory ended there, so he must not have had anything to say.
"That didn't explain a bloody thing," Severus informed the Pensieve. The memory had ended abruptly, and he'd found himself standing in his dining room again. There were all the things other-Granger had put in her bag, and there was his handwriting on the potion bottle.
Severus watched the memory a dozen more times. He noticed something different each time: The numbers in Granger's handwriting covering the exposed pages of an overlarge workbook, arithmancy equations. The sure way they worked together, as though they'd been at it for a lifetime. The perfectly alphabetized store room. The low stool at the corner desk with a well-padded cushion. His own handwriting across ledgers and invoices on the desk itself. A pair of reading glasses in old-Severus's breast pocket. The house elf (wearing a clean green pillow case-toga) that appearing for a split second at the end of the memory, opening the door to the lab with worry in its bulbous brown eyes. The way the hundreds of vials in the room were arranged first by medium (crystal with crystal, glass with glass, lead with lead, etc.) and then by size.
Severus paced. Sometimes, it helped him think, but not this time. He paced and his mind continued to be blank, completely void of any useful idea. Eventually, he stopped pacing and made himself a sandwich. The food didn't help him think.
He watched the memory again, then again. He memorized the arithmancy on the workbook and wrote it out again, trying to balance the equations or find some reasoning behind them. (Nothing came of it.) He did the same with the names on the ledgers and invoices, though no amount of wracking his brains or his books showed results.
And then, just over twenty-four hours after the witch had vanished from his sitting room, Hermione Granger, aged thirteen, knocked on his front door.