So, I'm back with the third part of this series (I think that's what you would call it), I've decided to make each chapter longer, as they were really short before, so I won't be posting as often. Hope you enjoy!

They were in the bookshop. Aziraphale was trying to teach Crowley some obscure card game, and Crowley was trying to think of something else to do. Anything else.

Crowley had been looking forward to the summer, when things would go back to normal for a bit. No children or talking portraits or strange quests but he had to admit, this was boring. Without his demonic duties, Crowley did not really have a purpose. He understood what Aziraphale had said many times, it was nice to be needed.

"And when you have three of the same number and four of another…" Aziraphale was saying, "Crowley, are you listening?"

"Yep," Crowley stared absentmindedly at his cards. He had two kings, an ace and four threes. And he absolutely no idea what that meant, "do you want to go to the park?"

Aziraphale looked crestfallen, but he agreed. Crowley dropped his cards in relief.

"Why do you want to stop now Crowley? You've nearly won," Aziraphale asked.

"You know, quit while you're ahead," Crowley muttered, then turn to get his coat.

Did he even have a purpose et Hogwarts though, he mused. He had snuck onto the train with Aziraphale. He hadn't even been invited. Technically Aziraphale was the 'guardian angel'.

"Are you alright?" Aziraphale sounded concerned.

"Yep," Crowley said.

"You're just standing, looking at your coat."

"It's a nice coat."

"It is…"

Aziraphale paused, then added,

"I miss Hogwarts."

"Huh."

They walked to the door.

"Me too angel."

Crowley opened the door, ignoring Aziraphale's slightly shocked expression.

They walked a little way down the street before he spoke again.

"You were right."

"I beg your pardon?"

"You heard me; I'm not repeating it."

"About what was I right then?"

"It's nice, having a purpose."

"Yes," Aziraphale sighed.

They walked in silence again. However, they did not get far before there came a shout from behind them. Crowley turned round curiously, then nudged Aziraphale. He was something he needed to see.

There was a man, attired in a pinstripe cloak and a lime green bowler hat, running up the street toward them. Running did not suit him. When he finally caught up, he was bright red in the face and needed some time to get his breath back. He emitted an aura of distinct unease, his face worried and stressed, his movements quick and jerky.

"Professor Fell, Professor Crowley?" he asked.

If it hadn't been clear what he was before, and honestly the pinstripe cloak was a big giveaway, it was clear now. Aziraphale's face lit up with excitement, Crowley barely restrained a grin.

"Yes, that's us," Aziraphale replied, "How can we be of assistance?"

"Well," the man, the wizard hopped nervously from foot to foot, like a disgruntled robin, "is there somewhere," he looked about himself cautiously, "more private, we could talk?"

"Of course," Aziraphale smiled.

They walked back to the bookshop. The strange wizard was soon situated on the sofa, while Aziraphale made him a cup of tea. This was one place, Crowley thought, that he didn't look quite so out of place.

"Allow me to introduce myself," the wizard said, removing his bowler hat politely, "I am Cornelius Fudge, the Minister of Magic."

These words registered little with Crowley, except that Fudge seemed an appropriate name for this short and blustering man. But Aziraphale reacted quite differently.

"Minister," he exclaimed, "it's so good of you to grace us with your presence."

Crowley thought this was laying it on a bit thick, but Fudge seemed pleased. He gratefully accepted his cup of tea, then began to explain why he was here.

"I'm here on a mission of national security," he explained pompously.

"Really?" Crowley wondered why he was taking so long drinking tea if it was so important.

"It doesn't have anything to do with that, Black fellow?" Aziraphale asked.

The minister nearly spat out his tea.

"How did you know?"

"I didn't. He was just on the news the other night. It never said, where he was escaped from, so I felt suspicious. But I suppose now, he must have escaped from Azkaban."

"You are quite right," Fudge said gravely, "but unfortunately there's more. I understand you two were employed by Dumbledore in order to watch out for Harry Potter when he's at Hogwarts."

"That's right."

"Sirius Black is after Harry."

There was a shocked silence. Then Aziraphale spoke again.

"Why?"

"Black was one of You-Know-Who's most trusted servants. He killed twelve people in one go, before he was locked up in Azkaban. Now he's out, he'll surely be looking for Harry, the man who put his master out of business."

"But how did Black escape?" Crowley asked, though he had a feeling he knew the answer. He had gotten a feel already for the Ministry's level of competence.

"That's the thing. We've no idea. But he knows where he's headed. Before he escaped, Black was reported to be muttering in his sleep. 'He's at Hogwarts', he was saying 'he's at Hogwarts'."

"Of course, a number of measures have been put in place," Fudge went on conversationally, "the Azkaban guards have been stationed outside of the school. Dumbledore was not happy, but…well needs must."

"The Azkaban guards?" Aziraphale exclaimed, recovering himself.

"I'm afraid so," Fudge said, "It is necessary. Not just for Harry's sake but the other children too. Moany parents wouldn't let their children back into school otherwise."

He said it firmly, and Aziraphale got the feeling that he had had to explain it to many people before. Nobody was going to agree that dementors outside a school was even a remotely good idea.

"I understand," he said.

The Minister smiled. Then he stood up, drank the last of his tea and replaced his green bowler hat.

"Thank you for your time professors. Please remember that the Ministry has taken full control over Harry's security. He is in safe hands."

With these words, he left, waving cheerily as the bell on the bookshop door rang.

"I don't think he liked us," Crowley muttered.

"I don't think he likes Dumbledore doing a better job than him," Aziraphale said thoughtfully, "He was asked to be Minister for magic you know, and from what I hear, Fudge is always going to him for advice. Except this time, it seems. The Dementors! What was he thinking?"

"The wot-nows?"

"Dementors dear, they guard Azkaban, the wizarding prison. Horrible things! From what I've read, they effectively feed off happiness, sucking it out of a person."

Crowley gave a slight shudder,

"Huh. You know, they sound like a type of demon they keep in hell. Modern form of torture."

Aziraphale wondered whether Crowley's recent shudder had come from fear of the dementors, or hell.

"So, there are demons in the wizarding world?"

Crowley shrugged, "I could be wrong angel. They just sound like them," he was silent for a minute, then added, "they're pretty nasty, and I don't know what we'd do if we ran into them. I'd be fine of course, but if there were any humans around…"

He trailed off. What would happen to humans was clearly not something he wanted to describe.

"They have a spell I think, in the Wizarding World," Aziraphale said thoughtfully.

He hurried to the back of the bookshop, and removing several ancient looking bibles, he revealed a row of books which Crowley recognised as books on magic. Aziraphale pulled out a thin volume, bound in green leather, with fancy gilded writing.

"Protection Spells for all Occasions," he explained, sitting neatly on the sofa and opening the book. He leafed through it for a few seconds before clearing his throat and reading a passage.

"The Dementor cannot be killed but can be repelled. A person wishing to prevent a Dementor from approaching must channel happiness, through the form of a happy memory, as this represents an opposing force to the hopelessness, and sadness caused by the presence of the dementor. This can be done using a simple enchantment. Expecto Patronum."

"And why don't they teach this at Hogwarts?" Crowley asked.

"It is notoriously hard to do," Aziraphale said, "and it isn't on the NEWT exam syllabus. But this year…"

"It would probably be a good idea," Crowley finished.

"Well, in order to teach it, we'd better learn it first."

"Can we even do it? I mean, we're not technically wizards."

"We do spells at Hogwarts, don't we?"

"It's more just miracles."

"Yes, but we say the words and point the wands etcetera, etcetera…"

"Huh."

Now that they both thought about it, they had effectively been doing magic for a while. In their own celestial way.

"So how do you do it?"

They had decided to practice in Crowley's flat, where there was more space. Crowley was unimpressed with this arrangement, but Aziraphale talked him down. It was imperative that they knew this charm, both in their capacity as teachers and Harry's protectors.

Aziraphale studied his book.

In order to summon a Patronus, one must first think of a happy memory. The stronger the memory, the stronger the Patronus. The Patronus must be strong enough to survive, when faced with a real dementor.

"We need to think about a happy memory," he told Crowley, "that's the first step anyway. There's a lot in here. Corporeal and incorporeal Patronises, how to summon them when a dementor is in front of you, different forms and their relative meanings."

"Different forms?" Crowley asked, interested despite himself.

"Yes. They take the shape of animals. Apparently animagi generally have the same Patronus as their animal form, and their often hereditary."

"So, mine will be a snake."

"I suppose so. If it takes a corporeal form. Anyway, happy memories."

Both lapsed into thought. Aziraphale thought about some of his happiest memories. Feeding the ducks with Crowley, riding in the Bentley with Crowley, stopping Armageddon with Crowley… he was sensing a theme here. His eyes darted over to where Crowley sat, but the demon showed to sign of knowing what he had been thinking. Aziraphale focused on his task again. He focused on the moment when they had stopped Armageddon. When he had known that he was free to stay on Earth. With Crowley, his inner voice reluctantly admitted. Crowley was his best friend. Existence was better with Crowley.

"Have you got a memory yet?" he asked his friend.

"Yep," Crowley nodded.

He was lying. Crowley didn't really do memories. Crowley moved forward, forgot. He had done a lot of evil things in his existence and dwelling on them was not enjoyable. He tried not to think about plagues and wars and suffering, to find something happy. Happiness he hadn't felt due to someone else's downfall.

Aziraphale was consulting his book.

Once a memory is found, one simply says the charm: Expecto Patronum.

"Expecto Patronum," Aziraphale repeated softly.

"Wot?"

"Expecto Patronum."

Aziraphale stood up straight, miracled up a wand (angle feather core and sycamore wood), and thought hard about Armageddon.

"Expecto Patronum!"

Nothing happened. He tried again, thinking really hard this time, trying to block out all other thoughts.

"Expecto Patronum!"

He thought about Adam's fierce resolution to save the world he loved.

"Expecto Patronum!"

He thought about Newt, and Anathema, Madame Tracy and Shadwell. How happy they'd been when they knew the world wasn't ending.

"Expecto Patronum!"

A thin wisp of silver smoke drifted from the tip of the wand. Aziraphale studied his book.

The first Patronus formed is generally incorporeal, without shape. However, after the first, summoning a Patronus comes easily. It soon takes shape.

Aziraphale focused hard. He blocked everything else out. He thought about after Armageddon, he and Crowley dining at the Ritz. To the world.

"Expecto Patronum!"

This was the one, he felt it. Again, the silver smoke leapt from the wand. But this time it was far brighter, stronger. And it had a shape. A silver dove flew gracefully in the air above Aziraphale's head. It worked.

Crowley watched the dove as it looped and twirled around the room, flapping it's silver wings.

"A pigeon angel, well done."

"It's a dove," Aziraphale said indignantly.

"You sure?"

"Yes! I'm-"

But Crowley was smiling. Aziraphale smiled too.

"Come on then, you turn."

Crowley stood up. His mind was still racing with memories, and he couldn't find the perfect one.

"Expecto Patronum."

As he expected, nothing happened. Perhaps it was impossible for a demon to summon a Patronus. It went against his very nature.

"What did you think about angel," he asked, trying to make it sound relaxed, nonchalant.

Aziraphale went pink.

"Well, Armageddon, of course."

Crowley nodded slowly.

"It has to be something big, life changing. You know."

"Yeah."

The only life changing event Crowley could think of was the fall. He tried to think about Armageddon, but it wouldn't stick. All he could remember now was hell. Knowing he was trapped with this forever, though he hadn't really meant to come at all.

Luckily, he was saved from trying again, by a knock on the door.

A tall thin man stood outside, with greying hair and a long, patched coat. He looked worried, and Crowley could feel the chill of apprehension fill the room.

"Hi," he started, gingerly.

"Hello," the man gave a short nod, "Professor Crowley I presume?"

"That's me," Crowley had a thought, "You're not from the ministry, are you?"

"No," the man shook his head, "I'm from Dumbledore."

"What about Dumbledore?" Aziraphale hurried over, "Oh, hello, do come in. Crowley you really must let people in when they call. You can't just leave them on the doorstep. How can we help you?"

This last remark was directed at the shabby-coated man.

"It's about Harry Potter. He ran away from home."

By the way, I really meant to publish this sooner, but I honestly couldn't think of a name. I'm not sure I've picked the right one now, but I figured the story is probably a bit more important.