“Gran’pa, Gran’pa, Jamie says they’re going to leave me out under the blue moon tonight!”

Chuckling, Harry Potter bent down to scoop up his little great-great-great-granddaughter. Or was it four greats by now? He’d lost track. At six years old, Emily didn’t go any slower than full steam ahead these days.

“What’s this?” he asked, tucking the little girl securely onto his lap, and casting a discrete sticking charm, too. His reflexes weren’t as fast as they used to be, and Emily was a slippery little thing.

Emily frowned over her shoulder at where her older brother, James, was sauntering towards them. “Jamie says Mummy and Daddy are going to leave me outside tonight for the blue moon!” she repeated.

Harry raised his eyebrows. “There’s a blue moon tonight?” he repeated.

“Yeah. It’s a once in a lifetime event, Mum says,” James said.

Harry snorted. Usually it was once in a lifetime, but then again, his life had never been normal. His possession of the three Hallows had granted him a longer lifespan than most, and now, at almost the three century mark, it looked like he was going to experience a blue moon for the second time.

“Your brother’s just teasing you, dear,” he said to Emily. “Of course your parents wouldn’t leave you outside.” Emily stuck her tongue out at her brother, who just sneered at her in reply. Harry cancelled the sticking charm, and lowered her to the ground. “Why don’t you go ask your mother what a blue moon does.”

“Okay!” Beaming now, Emily skipped off, humming a tune that she’d made up on the spot.

Harry turned his attention to James. Despite the fact that James and Emily weren’t actually Potters anymore, James had inherited the unruly Potter hair of his namesake. The only thing that stopped him looking like Harry’s father reborn again were his silvery-grey eyes, gained – much to Harry’s chagrin – from a Malfoy that had had the temerity to marry his great-granddaughter.

“You shouldn’t tease your little sister so,” Harry scolded, but it wasn’t much of a scold. He just didn’t have the energy for it these days.

James rolled his eyes. “Well, tell her to stop annoying me and getting into my things, then,” he said.

Harry smiled. “Alas, I’m told that that is the entire reason that little sisters exist,” he said.

From his loftier age of nine, James pulled a face. “Can’t wait until I get to go to Hogwarts,” he muttered. Then he abruptly perked up. “Grandpa Harry, have you seen a blue moon before?” he asked.

Rolling on his back, then standing up and shaking blades of grass out of black fur. Play-bowing, tail waving madly, before attempting to shoulder-rush the black other. Muzzle lifted to the bright full moons, joyful pack-song echoing out into the night.

“Yes,” said Harry, finally, wistfully. “I have. Years ago; long before your time.”

“Did anyone die from it?” asked James, eagerly.

Harry looked at his however-many-greats grandson for a moment. The young boy knew nothing of war, nothing of death. To him, death was something that happened in a horror story. He had no idea of how intensely death could touch a person.

“No,” Harry said hoarsely. “Nobody died.” After all, Voldemort doesn’t count.

When the normal moon rose, Harry was sitting on the deck at the back of the house. He still vaguely remembered that Ron had roped in Fred and George – or had it been Bill and Charlie? – to help build it. The four of them had done quite well, they’d thought . . . until they’d come to walk over it at the end, and found it upending under their feet. Hermione and Ginny had laughed themselves sick at the sight the four males had made, before creating this beautiful deck with just a few waves of their wands.

He missed them, Harry admitted to himself. He missed them all fiercely. His bushy-haired friend and his . . . his . . . his red-furred mate.

Before he even realised it, his muzzle – grey to the point of pure white now – was pointing at the newly risen second moon, and a tremulous howl floated away on the breeze.

Oh, how different everything was. He was lying on cold, hard wood, and he couldn’t seem to summon the energy to get up. He should, he really should, but his muscles were stiff, and his joints ached. His ears felt like they were stuffed with something, and his nose was no better.

He whimpered to himself, resting his muzzle on his paws. He’d been alone before, and hadn’t liked it then, either. But now he was old. His pack was long gone.

Movement caught his eye, and he raised his head, useless ears pricking in that direction. A soft whuff of disbelief escaped him, and then a pleading whine.

The other was sitting not that far distant from him, not looking any older than the last time he’d seen the other, dense black fur still as shadowy as ever. The other tilted his head encouragingly at him, obviously waiting for him to bounce over and demand to play.

He whined again, and dropped his head to his paws again. He wanted to play. It had been so long since he’d seen the other – two centuries since Severus died, something deep inside whispered in a mournful voice – but he just didn’t have the strength anymore.

Eventually, the other seemed to realise this, and padded silently over to sit beside him. He turned his head and snuffled, but the other was strangely scentless. Then again, perhaps that was just his nose not working anymore. The other lowered his head and snuffled in the fur at the back of his neck, then gave a quick lick over the top of his head.

Abruptly, there were teeth in the scruff of his neck, tugging upwards. He yelped, and pulled himself free with a quick wriggle, before turning his head and growling at the other in protest. All it earned him was a sharp nip on one of his ears – which caused him to yelp again – and the teeth took a firmer grip on his neck.

Eventually, after two more fruitless attempts to get free, he realised that the other was trying to get him up off the ground. So when the other tugged at him again, he pushed with his forelegs until he was sitting on his haunches, panting heavily.

The other gave him an encouraging lick, and then began nudging him. He whined, pitifully, his ears drooping. His inner puppy wanted nothing more than to gambol and play with the other, to be free in a way he hadn’t been in so long, but his outer shell just wasn’t capable of that anymore. He was old, and tired, and aching.

Finally, getting fed up with the constant head-nudges – although they weren’t forceful enough to push him over again – he gave in and shakily rose until he was standing on all four paws. There was a moment where he wasn’t quite certain that he wasn’t just going to crash straight down again, but then his muscles stiffened, and he remained upright.

The other gave a pleased whuff, and moved round in front, so that he was face to face with the other. Then the other took a slow step backwards.

Although this seemed incredibly odd behaviour, he willingly allowed himself to be manipulated into moving ever so slowly off the cold, hard wood and onto the soft grass. Surprisingly, once his paws touched it, it seemed to become easier to move, so that by the time the other had backed almost the entire length of the garden, he was all but gambolling like a puppy again.

Feeling as though a weight had been lifted from him, he yelped with delight, then bounced into a play bow, his tail beginning to wag.

The other sat down on his haunches and regarded him, almost sadly. But that was ridiculous. The night was young, the moon was bright, he was pain-free again . . . what could possibly be wrong with that?

Without warning, the other suddenly rushed at him, bowling him over. They rolled around in a ball of tails, teeth and paws, the other mock-growling, and him yelping and barking. Wriggling free, he rolled himself up onto his feet, shook his coat briefly, then pounced back at the other’s tail. Unfortunately, the other moved, and he ended up with a mouthful of ear, instead.

He considered – very briefly – giving it a quick nip, but the other’s teeth were now very close to his own ears, so he just spat it out instead. The other rolled underneath him, taking his legs out from under him, and he went sprawling headfirst over the other.

The other sat up, head tilted in amusement, then the other’s muzzle lifted, and a high-pitched, singing howl emerged.

Sitting up himself, he felt the answering song crawling up his throat, and before he knew it, his own muzzle was tilted towards the sky, his song a counterpoint to the other’s. They were pack. He was home.

The other’s muzzle lowered, and with a tilt of soggy ears, suddenly the other was bounding away across the grass. With a laughing yelp of ‘wait for me!’, he bounded after the other, not noticing that with each bound, they were slowly fading away.

They found Harry’s body in the garden the next morning. He looked peaceful, and happy, but they couldn’t understand it. Why had he been outside when he knew full well there was a blue moon?

Resigning themselves to never knowing, they took him away and buried him in the old heroes’ cemetery. And if, on certain nights, the shadowy figures of two wolves played in the grounds of that cemetery . . .

Well, there was nobody there to disturb them.