Time was something that Crowley had never really worried about (being immortal has its perks), but Halloween came along so quickly he thought that Time may have been tampered with. The school was once again buzzing with rumours about the feast, the entertainment, and the Halloween trip to Hogsmeade, the village near Hogwarts castle. With the normal hubbub of students and teachers alike preparing for the celebrations, there came a new notice in the staff room. A rotation of teachers was going to accompany the students to Hogsmeade that year, as an extra precaution against Sirius Black. As he went to search for his name, Aziraphale wondered why the students had gone unaccompanied to the village before. It didn't seem wise.

"You two are going down next time," McGonagall said, coming up behind them, "it's right before Christmas, and we decided that, with so many students likely to go, we would send the experts."

Crowley often forgot that he and Aziraphale were supposed to be some kind of freelance aurors. He nodded in understanding as Professor McGonagall went on.

"By the way, if Potter comes asking for one of you two to sign his Hogwarts permission form, please say no. For his own safety."

She sounded genuinely worried.

"Permission form?" Crowley asked, non-plussed.

"All students need to get a permission form signed by a parent or guardian to visit Hogsmeade on weekends," McGonagall explained.

Crowley felt that this was a serious double-standard considering the safety of Quidditch and indeed normal life around the school, but McGonagall's serious tone told him now was not the time to argue. They both agreed not to sign Harry's form.

…

"I reckon it would do him good to get out of the castle," Crowley told Aziraphale later. The angel shrugged wearily; he was going through the files they had on Sirius Black's crimes.

"There's really no point in going through them again angel," Crowley said, gesturing to the stack of parchment, "We're at a stalemate. The only thing that will take us forward in this investigation is talking to Lupin or finding Black. And-"

"I know Crowley," Aziraphale sounded exasperated. He had heard Crowley's view on the subject too many times, "we can't find out wear Black is without personal information on him, which could tell us how and where he is hiding. And to get that, you thin-"

"We both think."

"Fine. We both think we would do well to ask Lupin about Black. But we-"

"You."

"I don't want to betray his trust."

"Even though we've known him a while now and spent plenty of time with him."

"Despite that."

They had been going over to Lupin's classroom almost daily for the last few weeks, and spent pleasurable hours discussing magical creatures, a subject on which Aziraphale and more surprisingly Crowley, were very well versed. It turned out that hippogriffs were not the only creatures that Crowley was interested in. What with this and making sure the syllabuses for Care of Magical Creatures and Defence Against the Dark Arts didn't overlap too much by planning lessons together (the third year DADA syllabus in particular included a lot of magical creatures), they were becoming closer.

Aziraphale however, to Crowley's annoyance, was not accepting this as enough for them to ask Lupin what he knew about Black. Crowley had been patient, Aziraphale knew people better, he understood them, but now he was sick of waiting. They needed to get this over with, for Harry's sake.

"How about we ask him after the feast?" Crowley suggested.

"Maybe…"

Aziraphale wasn't only keen to keep on good terms with Lupin. He honestly wasn't sure Lupin trusted them enough to tell them anything useful. He kept thinking back to what Hagrid had said, and wondering what was going on with the Professor, and why he hadn't told them. He hadn't even admitted to knowing Sirius Black yet, even though the name was all over the school, and hadn't brought up his time at Hogwarts at all either. Aziraphale didn't feel they needed to keep Lupin's trust; they needed to gain it. He did not feel prepared to ask him about Black after the feast.

…

But Lupin was not at the feast. He was ill, apparently, as they were told by a sneering Professor Snape. Aziraphale, too relieved to be really worried, sat back watched the third years file into the hall, most of them flushed from the cold walk from Hogsmeade. Harry was among them, looking glum, clearly upset that had not been to Hogsmeade with the others. He had not asked either of them to sign his permission form, which was another relief. Aziraphale had not wanted to have to tell the boy no.

The feast was the same as ever, and Aziraphale was pleased to see Harry looking happier, as the deserts finally disappeared.

They left the great hall with the other teachers after a speech from Dumbledore and the entertainment (this year provided by the Hogwarts ghosts), but had not yet reached their rooms when Percy Weasley, red-faced and breathing hard, ran up to them.

"Professor Dumbledore sent me," he gasped, still managing to sound pompous, "there's a problem."

"What problem?" Aziraphale said, immediately thinking of Black, who had been occupying his thoughts for some time now. His fears were confirmed by Percy's face.

"He tried to break into the Gryffindor common room," he explained, not bothering to say Black's name, they all knew who he was talking about, "attacked the Fat Lady with a knife when she wouldn't let him in."

Aziraphale saw Crowley's eyes widen behind his glasses. This was a new development, and one they couldn't explain. Apart from the murder of Pettigrew, Black had shown no other tendencies toward violence of that kind. Aziraphale was beginning to wonder is Azkaban had sent him mad. Thank goodness Harry had been at the feast. One day earlier and Black might have done some real damage.

They hurried back to the great hall at once, and met Dumbledore, who was calm and serene as usual, although his blue eyes had lost their customary sparkle. He addressed all the teachers who were gathered in the hall, his voice grave.

"This is a wholly unexpected occurrence, and therefore we have no predetermined procedure. I would suggest however, that all students should be bought here to sleep, and meanwhile, we teachers will search the castle and grounds. The head boy and girl," he gestured to Percy, who swelled with pride, "will be left in charge of the younger students."

There were murmurs of assent, accompanied by tense nods. The teachers were all as shocked at Aziraphale and Crowley clearly. Nobody had expected Black to actually get inside the castle. All the more reason to speed the investigation up a bit, Crowley thought, and he could tell Aziraphale thought the same, and didn't like it. Dumbledore started telling the teachers where he would like them to search first.

"Professors McGonagall and Flitwick, please take the towers. Professor Snape, please could you take the dungeons with Professor Sprout. Professor Crowley, Professor Fell, take the grounds. Hagrid had better go too, we must make haste."

…

It was very cold in the grounds. The sky was black, clouds covering any stars which could have been seen. A chilly wind blew occasionally. Crowley wished they could have been assigned any other place. In the distance, Hagrid's great lantern could be seen. Aziraphale carried a similar one, which lit up the frosted grass in front of them in a warm beam of light.

"We've done the greenhouses," Crowley said, "and Hagrid said he's done the edge of the forest."

"And Hagrid is doing the Quidditch pitch," Aziraphale added, "I'd say we only have the lake to go."

He shivered a little, and not just from the cold. The prospect of skirting the mysterious waters of the lake, in the dark, was not exciting. Nonetheless, they turned their feet toward the expanse of murky water, the torch beam spread out before them.

It took them about half an hour to circle the lake, during which time they talked little, and when they did only about the whereabouts of Sirius Black. Neither one wanted to discuss the fact that he truly did seem to be after Harry, when they had been almost certain he was somehow innocent.

Aziraphale gazed across the water thoughtfully, when they had circled the lake twice, just to be sure. His eye fell on the tree under which he had spoken to Hermione. He started in surprise and clutched Crowley's arm, pointing at a dark shape under the tree. The demon at once looked where he indicated and saw it too. A large, black dog. it sat in the shadow of the tree, but the lights of the castle in the distance meant that it could just be seen.

"Do you think it's the same one?" Aziraphale hissed, his voice sounding horribly loud in the general silence all around them.

"That's no ordinary dog," Crowley whispered back, "if I didn't know better, I'd say it was a hellhound."

He was right. There was an alertness, almost a consciousness about the dog, which suggested it was more than what it appeared.

"It feels," Aziraphale hesitated, not sure what to say. Crowley finished his thought.

"Human."

…

"That's it, angel, we are talking to Lupin."

Crowley paced their room. He was not going to waste another second arguing over putting their friendship with Lupin under strain. They had now discussed the Black dog at length and had decided that it was no coincidence that it had appeared the very night that Black had broken into Hogwarts.

Aziraphale nodded slowly. He agreed.

"He's still ill though," he pointed out, then added, "but you could go and speak to Harry."

"What?"

"Tell him you saw his mysterious black dog. Reassure him it isn't a death omen?"

Crowley paused in his pacing. He had forgotten about that. He should go and reassure Harry. He strode to the door.

"You're right angel, I should."

He left, leaving Aziraphale feeling rather bewildered. He wondered if he could get the demon's last words in writing.

…

"Potter," Crowley called to the boy's retreating back. He was deep in conversation with Oliver Wood. They were most likely discussing the upcoming Quidditch match. Harry turned when he heard Crowley. Oliver Wood stopped beside him but kept speaking.

"I need to talk to Potter, Wood," Crowley said, and Wood went on, looking disappointed.

"Thank you," Harry said with a grin, "he won't stop giving me Quidditch tips now the match is coming up."

Crowley grinned back, then looked serious.

"I saw your black dog," he explained, deciding to cut right to the chase.

"Where?" Harry asked.

"In the grounds, when we were out looking for Black the other night."

Harry looked at him expectantly.

"Well, it isn't a Grimm," Crowley said.

Harry looked relieved for a second, then confused. Crowley realised that something in his tone must have given away that the dog, despite not being a Grimm, was not just a dog either.

"What is it?"

Crowley hesitated. He didn't want to lie to Harry. Dumbledore had said they wouldn't be able to help him much longer. He couldn't face his destiny if he had been lied to about danger all his life.

"I'm not sure," he finally said, "but I don't think it's dangerous."

That much was true at least. The presence of the dog was not dangerous. It felt conscious, human even, but not like an evil human.

"Don't go looking for it in the grounds though Potter," Crowley warned, "I said, I think it's not dangerous."

There was no need to remind him that Black was after him, as Crowley was sure he already knew and was reminded several times a day. He thought Harry might have noticed that he didn't mention Black, as he looked at him with genuine respect. A good half of a conversation is unspoken, and this was one such conversation.

"Well," Crowley turned to leave, "good luck in the match."

"Thank you," Harry said, but it was clear his mind was elsewhere. Crowley had given him something to think about.