It was a Saturday afternoon, the weather still sunny and warm, as September hadn't quite got going yet. Aziraphale looked longingly out of the window as he left for breakfast, imagining a day spent reading by the lake, soaking up the last of that year's sunlight. However, it was not to be. The task of interviewing Snape fell to Aziraphale, as Crowley had spoken to Harry. The demon still wouldn't tell Aziraphale exactly what he had said to Harry, but Harry seemed more cheerful, and that was what mattered. Aziraphale had been concerned to hear about the black dog, though Crowley had thought he was being superstitious. Was it the same one that man had seem in Diagon Alley? Aziraphale had a strange feeling it was connected somehow.

After breakfast he made his way reluctantly to the dungeons below the castle, where the air was sour and stale, and the only light came from the flickering torches in their brackets. Aziraphale had never quite got to grips with the twenty first century, but right now he missed modern technology. A simple lightbulb was taken for granted in the muggle world. It really was no wonder that Snape was so bad-tempered, spending all his time in a place like the Hogwarts dungeons. Or perhaps the dark, dripping dungeons attracted his gloomy personality.

Snape was first on their list of people who could aid them in their 'enquiry'. He had a grudging alliance with Aziraphale and Crowley and could be trusted to keep their task a secret, largely because they knew his. But relationships with Snape, despite their tenuous alliance, were strained. Snape did not seem to like that they had an advantage over him. He hadn't taken Aziraphale's advice to become a better person either. He still hated Harry, and it seemed, everyone else.

Hagrid and McGonagall were next on the list, as they had almost certainly been at Hogwarts at the time of Sirius Black and were part of the Order of the Phoenix. Aziraphale thought that speaking to them would be a much more agreeable task.

He was dragged from his musings by Snape, who swept out of one of the labyrinthine dungeon corridors, heading in the direction of his office. He reminded Aziraphale of a vampire he had met whilst travelling in Transylvania. He hurried after him, hoping to catch him before he shut himself in his office.

"Professor Snape," he called, trying not to flinch slightly was the hook-nosed Potions master whirled about, glowering at him.

"How can I help you?" it sounded like an insult. Or a death threat.

"I was wondering if I could ask you some questions?"

"About Sirius Black?"

Aziraphale was taken aback, and Snape saw it on his face.

"Believe it or not, I happen to be in Dumbledore's…inner circle. I know about things."

Aziraphale tried for a smile.

"Well, could you help me?"

"I told Dumbledore I would. He already knows much of this, but it will probably aid you…investigation."

Aziraphale thought, in a moment of bad temper, that maybe Dumbledore should have carried out this investigation himself or told them all that he knew before they started. But the headmaster worked in mysterious ways, and after all, they hadn't actually asked him. Aziraphale swallowed his frustration, and this time managed at least a semi-pleasant smile.

"That would be extremely helpful, thank you."

They went into Snape's office, a place that Aziraphale had hoped never to revisit. The slimy things in jars were still there, floating about eerily in their different coloured solutions, arranged on shelves among ancient books, spotted with mould. Snape sat down behind his desk and gestured for Aziraphale to take a seat on the other side.

"Didn't bring you, colleague?" he sneered.

"No," Aziraphale replied, his voice calm and polite, "Now, what can you tell me about Sirius Black."

"Well, he was best friends with Potter for starters," Snape scowled at James Potter's memory, "and that Remus Lupin. The four of them, Potter, Black, Lupin and Pettigrew. Of course, Potter and Black were the ringleaders, but the other two weren't much better. they all thought very highly of themselves," he frowned even more deeply. Aziraphale wondered if he would actually be able to get his face back to normal.

"Remus Lupin?" Aziraphale was surprised at first, then a memory struck him then, and he mentally kicked himself. He should have seen it before.

"Yes. James was actually one of my best friends. We joined up together. Us, and…some others."

The others must have been Black. And this Pettigrew.

Snape was still sneering at him, relishing exposing Lupin's friendship with Black like this. Aziraphale felt a hot flush of anger creeping up his neck. He didn't get angry often, but Snape was crossing a line, trying to make Lupin look bad because of things that had happened years ago. He controlled himself with an effort as Snape went on.

"Yes, he and Lupin were good friends, I'm surprised he didn't tell you," Snape smirked, "Probably trying to protect his reputation. He always turned a blind eye to Potter and Black's antics."

"I never asked," Aziraphale said staunchly, "and I really doubt it makes much difference. It's been twelve years since they saw each other. And I doubt Lupin would want to get involved with someone who betrayed on of his best friends."

Snape scowled, which made Aziraphale feel smug.

"What about Pettigrew?" he said, "what happened to him?"

Now it was Snapes turn to feel superior.

"Did you do any research? Peter Pettigrew. Surely you've heard of him?"

Aziraphale gave a start. Peter Pettigrew. The wizard that Black had killed along with all those muggles. He had been Black's friend. Aziraphale didn't know what to take from this. On the one hand, Sirius Black was very guilty. He had as good as killed two of his closest friends. On the other he had as good as killed two of his closest friends? Why? It didn't make sense.

"Yes, I've heard of Peter Pettigrew. Black killed him."

"All they had left was his finger," Snape remarked with something bordering on relish. Clearly his hatred of James Potter extended to his friends as well. Aziraphale had an idea of what James and Sirius' 'antics' had included. But he wasn't here to find out about that. He still had one more idea.

"What about among the Death Eaters?" he asked.

Snape looked taken aback.

"What do you mean?"

"Sirius Black was supposed to be Voldemort's right-hand-man. Did you hear anything about him, see him, while you were working with the Dark Lord?"

"We didn't know much about one another," Snape said sharply. He spoke quickly, and in an undertone, as though the walls had ears, "it was a…security measure. One Death Eater couldn't give away too many others. It stopped uprisings too, you never knew who was on your side."

Aziraphale shuddered a little. He felt almost sorry for Snape. Being one of Lord Voldemort's Death Eaters did not sound pleasant.

"But no," Snape finished, "I never heard anything about Black. And I was right in the Dark Lord's inner circle. Most Death Eaters would have said I was his right-hand man."

There was no pride in his voice, no threats. Aziraphale realised that Snape could be dangerous. The man was an enigma. Nobody could quite say where his loyalties lay.

"And it didn't occur to you to say any of this when a possibly innocent man was being put into Azkaban as a Death Eater?" Aziraphale asked.

"Everyone saw him kill those muggles, and Pettigrew too, Death Eater or not. Besides, nobody was going to believe me, even if I wanted to stick up for the him. I was a suspected Death Eater myself."

Aziraphale couldn't argue with that, though he still felt that Snape had enjoyed seeing his old enemy being locked away.

"Well," he said, standing up, "Thank you for your time."

Despite the rather disagreeable interview, he had received some useful information. He decided to check the records again tomorrow, to see what he could find out about James Potter and Sirius Black. By the sounds of it, the best place to check first would be Filches office.

He was reluctant to talk to Lupin, although he would probably be able to supply them with useful information. Aziraphale wanted to be sure that he trusted them, before they went asking him about Black. They had been friends at school, joined the Order together, even if they weren't friends anymore. But Lupin might think they were accusing him of somehow being an accomplice in Black's escape. Far from needed to be on good terms with Lupin, Aziraphale didn't want to lose that friendship. He liked the Care of Magical Creatures teacher.

But right now, there was still plenty of time for that book by the lake, to give his thoughts some time to settle.

…

After some time, Aziraphale managed to convince Filch to let them search the records in his office, a process which involved a lot of flattery and a promise to ask Dumbledore about the use of thumbscrews in the future. It was well worth it though as the records in the office proved to be a positive gold mine of information. Sirius Black and James Potter had been even worse than the Weasley twins. Crowley had thought it was all hilarious of course, and Aziraphale had to admit, he had wondered where Harry had got it from, when he decided to drive a flying car to school. However, some of the detentions were troubling.

"Here's another one," Aziraphale said, looking up from a yellowed sheet of parchment, "caught hanging Severus Snape upside down from the battlements. They really didn't like him."

"Well, it explains why he hated them," Crowley leaned back in his chair, grateful for a rest from hunching over the papers, trying to decipher the faded ink, "I reckon he deserved it."

"What if he didn't though?" Aziraphale asked, "What if they were just…bullies."

"Lots of kids are angel," Crowley wasn't sure why Aziraphale was getting so worried about this, "they grow out of it. And it looks like the only person they ever did anything to was Snape. There's a few of his detentions in here too, so it wasn't like he didn't fight back."

"But what about Harry?"

"What about him?"

"If he finds out his father was…well, he thinks very highly of him. McGonagall told me. He'd be crushed if he found out."

Crowley was quiet, and Aziraphale knew he understood.

"There's really nothing we can do about its angel," he said quietly, "if he finds out, he finds out. His father did a lot of other things, in the Order of the Phoenix. He sacrificed himself to try and save Harry. I think that's more important than hanging Snape off the battlements."

"I just feel sorry for him," Aziraphale went on, "he doesn't know these things about his father, which is good, but he doesn't really know much about him at all. He's got nobody to tell him about James. He doesn't even know about Lupin."

Crowley sighed. He really didn't want to get involved with Harry's personal life. Their task was to find out if Sirius Black was innocent, not discover all they could about James Potter.

"Come on," he stood up, "I think we've got all we need from these records. Sirius Black was a prankster at school. He didn't like Snape. It doesn't tell us whether or not he is innocent."

They left Filches office, having carefully tidied away the old detention records.

"It doesn't add up," Aziraphale mused, "he wasn't in detention for anything like using an unforgivable curse. Snape didn't hear about him in among the Death Eaters. The people he hurt most in the war were his best friends. Crowley," he paused, "I know we haven't got any evidence to prove it, but I think Dumbledore was right. I think he's innocent."

Crowley nodded, but before he could speak, Aziraphale went on.

"We should talk to Hagrid. He can tell us about Black when he was in the Order, and whether or not he was involved with the Death Eaters at school. I heard that Voldemort had a following, even in Hogwarts."

"We need to talk to Lupin," Crowley said, "he knew him well. He could tell us where he might be hiding, even how he escaped."

"I don't want to yet Crowley," Aziraphale replied, "we need to wait. We've barely known him a few weeks."

Crowley said nothing. He agreed, but he didn't want to. They needed to speak to Lupin. Then they needed to track down Black.