Only Minerva had known his secret, and Minerva was dead.

He’d asked her to teach him how to become an Animagus last summer, when the long days had stretched in front of them with nothing to fill them. Whether he had wanted to prove that he could do anything the Marauders could, or whether he wanted something utterly divorced from the battle against Lord Voldemort, it soon became an opportunity to spend more time with Minerva.

Not that he’d fancied her, not at all, but he had found her brusque friendship soothing. Unlike Dumbledore her concern wasn’t tainted with the worry that he would be unable to spy for the Order, and unlike the others she took it for granted that he was truly on their side.

He hadn’t been surprised when his Animagus form was a black cat.

“How very appropriate,” she’d said, when he first transformed, and smiled. Smiles were precious by then, hard won from all of them. He’d butted his head against her knee and purred, able to say as a cat what he couldn’t as a man.

Maybe she’d been prescient, maybe it was Gryffindor thoroughness, but she’d warned him then of the dangers of staying too long in his Animagus form. “Cats are simple creatures, with simple thoughts; it can be seductive.”

“I’m no Sirius Black to have my mind so easily turned,” he’d scoffed, as soon as he’d turned back into Severus Snape.

Now he knew what she meant.

Afterwards, when he was no longer needed, he’d started spending more time as a cat. He’d discovered that though the Dreamless Sleep potion no longer worked, sleeping as a cat meant he was disturbed by nothing worse than thoughts of his territory being invaded by Mrs Norris or juicy plump mice.

Cat’s thoughts were simple, sharp and clean: all jump and run and prey; the joy of the kill; the hot flood of blood in the mouth and none of the guilt.

As the year wore on, he’d spent more and more time as a cat. Detentions were now a rarity, or spent with Filch; he wanted nothing more than to spend his evenings drowsing on the rug before the fire in his quarters.

Until she came. Granger. Who sat in Minerva’s chair and took Minerva’s classes and got in the way. Mercifully even she had balked at taking on Minerva’s rooms.

Once he’d rounded on her in a staff meeting and demanded what on earth she thought she was doing, trying to take Minerva’s place.

She hadn’t replied for a while; just sat there white-faced and so grief-stricken that he felt moved to apologise, then said with quiet dignity, “Because she asked me to.”

She’d left him sat there, unable to find anything to say to that; none of his colleagues would meet his eyes.

It was then he started to venture out at night, still in cat form; his feet took him often to Granger’s corridor. She worked late; the light would shine out from under her office door until the early hours, and then she would stumble off to her chambers looking tired and worn.

One night he grew careless, or maybe he wanted to be seen. “Hello, there,” she said. “I haven’t seen you before. You’d better be careful, if Mrs Norris sees you, there’ll be trouble.” She’d bent and scratched him behind the ears; he submitted to the caress.

It was the start of a nightly ritual. He would always be there at the end of the day to greet her and escort her to her rooms. He didn’t think too closely about what he was doing, but allowed himself to be petted and cosseted, and lured into her room for milk and conversation.

Her lap was more comfortable than his rug, although he did have to put up with a constant flow of conversation just to have his tummy rubbed. She talked about her friends, she talked about her parents, she talked about how difficult it was to be a teacher, but she never talked about Minerva, not for a long time.

It was at least six months before the subject of Minerva was broached. By that time Hermione wasn’t working such terribly long hours, and they had settled into a routine of Severus dropping by in the early evening after dinner and sitting on her lap as she read or discussed the events of the day.

At first it was a simple comment about Minerva liking a particular book or how much she would have enjoyed seeing the roses in the garden. Then it was more detailed reminiscences: the first time she’d seen Minerva when she came to the castle, what she was like as a teacher, how supportive she’d been when Hermione had been in her seventh year.

Severus wanted to talk to Hermione about Minerva, but he couldn’t, not as a cat. He wanted to remember what she was like in staff meetings, the way her nose would wrinkle when Albus would make one of his sillier suggestions. He found himself sitting next to Hermione at staff meetings, always on the verge of saying something but never quite able to articulate it.

The silence wasn’t uncomfortable though; it carried something of the content he’d found in her company.

Then, one evening, when he was purring on her lap, she started talking about Minerva’s last moments. How she’d been brought gasping and shuddering into the Infirmary: Crucio, obviously, but that wasn’t what killed her. A dark hex, cast by Lucius Malfoy, and gone undetected at first, had started to leech the life from her.

She didn’t die easily, though Severus had seen enough of death to know that no one did. Whether it was stiff-upper lipped calm or screaming for mercy, death was death, and generally unwelcome.

No one had told him this. No one had dared tell him the truth, preferring to fob him off with platitudes and banalities. It was easier to hear the news with his dulled sensibilities, but not easy.

She faltered, and the hand caressing his head stilled. “The last thing she said,” her voice thick with tears, “ was to ask me to look after you.”

Snape fled, four paws skittering on the floor as he bolted for the door.

In the safety of his quarters, he shifted out of his cat form and paced the room. She’d made a fool of him. She’d known who and what he was all along. She’d been laughing at him. She’d stroked his tummy.

Dear god, what was he going to do.

That night he cried for Minerva for the first time, and the last. All of the grief he’d deferred came pouring out of him, and left him feeling curiously relieved and slightly empty.

He didn’t dream that night.

Breakfast was subdued. He sat as far away from Granger as possible. He could tell the other teachers were curious about why they were breaking the habit of the last couple of months and sitting apart, but no one asked.

His pupils were quick to spot his uncertain temper and behaved themselves leaving him unwelcome peace in which to think, and his mind kept turning to the sense of peace he had found in her rooms.

He wasn’t ready to talk to her at lunch, or even at dinner, which was conducted in an oddly expectant silence as they sat side by side.

So it seemed only natural that later his two feet should take him to Hermione’s rooms as usual, and that she should open her door to him and smile.

“Hello, Severus.”

Severus hovered at the door for a moment, before accepting her invitation to enter. It was peculiar sitting in her room and on her sofa, and actually having to think of a topic of conversation.

“So,” she asked, bridging the gap. “What is it like being an animagus?”

He found that the words came easily after his long silence, as if he’d been storing them up just for this.

And when she laid his hand on his sleeve and asked if he could teach her how to be an animagus too, he had a vision of two cats prowling Hogwarts’ corridors together.