Author's note: as you've probably noticed, what started out as a Harry Potter/Discworld crossover has become definitely a Harry Potter/Divine Comedy crossover by now. Anything in this story not owned by J. K. Rowling or Terry Pratchett is owned by Dante Alighieri or (in the scene with the Head Death in Chapter Two) by David Morgan-Mar, creator of Irregular Webcomic. I don't make any money out of this, but, as Morgan-Mar self-publishes for free on the internet and Dante has been dead for seven hundred years, neither do they.

It was nearly dawn in another country when the boat reached its destination. It was still dark enough to see the Southern Cross and the Southern Triangle, Centaurus, and the Phoenix: all constellations Severus had never seen except in photographs. The four stars of the Southern Cross represented Courage, Justice, Wisdom, and Self-Control, though in this place it was unlikely that people were sorted into groups according to which of these qualities they possessed or aspired to. They would need all four to climb the mountain that loomed ahead of them as the sky lightened.

The boat pulled up onto the shore, and the angel stepped out and held onto it while its passengers climbed out. When everyone had disembarked, he waved a wing to gesture to a colleague to take the boat on the next trip, while he shepherded his group onto the beach.

An old man who had been watching nearby made his way stiffly down to meet the newcomers. His long white hair, plaited into two braids, fell forward on his chest to mingle with the whiteness of his beard and the whiteness of his toga. Only around his stomach was the material torn and stained with blood.

Though he was as white-bearded as Dumbledore, there was nothing twinkly-eyed about this one. In the starlight, the new arrivals could see him glaring at them, and at the angel.

'Do you mean to tell me this rabble are allowed in?' he demanded. 'Not just non-Christians, but non-humans and witches? I swear the entry requirements are getting laxer every year!'

'More than when you came here, Marcus?' enquired the angel with a smile. 'You aren't a Christian yourself – and if you're going to be legalistic, many people consider suicide a sin.'

'I'm glad I did it rather than live under a dictator!' retorted the man. 'And it took me two tries, thanks to bloody doctors trying to save my life!'

'Understood,' said the angel. 'And you should know that this wizard here gave his life in fighting to rid the world of another dictator.'

The man called Marcus considered this for some time, and eventually held out his hand to shake Severus's. 'Good for you, boy,' he said gruffly. 'Did you succeed?'

'I don't know, yet. I hope so.' If Potter even bothered to look at the memories Severus had given him, and realised he needed to sacrifice himself – and if he actually did sacrifice himself – and if that really would defeat Voldemort, and wasn't just another subterfuge.

'I didn't. But it was worth it for trying, anyway. Pleased to meet you. Marcus Portius Cato.'

'Severus Snape.'

'Welcome to Purgatory. You'd better get a move on, now – there'll be boatloads more people arriving, and you can't all doss around at the foot of the mountain.'

'By the way, Marcus,' said the angel, 'the offer's still open for you to begin your journey, as soon as you feel ready. The same condition applies as before: you and Publius Vergilius Maro have to make the journey together.'

'That Imperialist lickspittle poet? I'd rather go back to the Ninth Circle!'

'Hmm. When you were acquitted of treason and transferred from the lower Hell to Limbo, it was Publius who came down there to escort you back, wasn't it?'

'It was. And why he wasn't condemned to the Eighth Circle as a flatterer, I can't imagine.'

'No, you can't, can you?' said the angel. 'But all the same – did Publius insult you for opposing Caesar's rule?'

'Well – no,' Cato admitted. 'I suppose he's not that bad, for an Imperialist.'

'And a few years later, when you were freed to come here and he wasn't, did he complain?'

'No. He said they'd want a good Roman to keep an eye on a place like this, and he couldn't think of anyone better qualified than me. Mealy-mouthed little twit! Anyway, he did come through on a visit, about seven hundred years ago, the time they let that living man in on a tour.'

'Exactly. So he knows the way up the mountain. He'd be happy to accompany you to Heaven, if you'd like to have a companion from your own time and culture.'

'Yes, but it's him!' groaned Cato.

Severus realised that, while he had been listening to this conversation, the other travellers had all dispersed, and all fallen into conversation with old friends or relatives, or with people they had always wanted to meet (except Ribby the elf, who had decided to stay with Doreen). It really was just like starting school – and realising that everyone else there seemed to be either a Pure-blood who had grown up immersed in the wizarding world and was surrounded by cousins and family friends, or else so naturally sociable and likeable that they could make a new Best Friend Forever just by stepping onto Platform Nine-and-Three-Quarters.

At least the first time round, getting on the Hogwarts Express for the first time, he'd had Lily's company – at least once Lily had stopped being in a bad mood after quarrelling with that ghastly sister of hers, just because Petunia had found out that Lily and Severus had been reading her letter from Professor Dumbledore…

Come to think of it, Severus realised, if he'd had a sister who used to sneak into his room with her friends when he was a teenager, how would he have felt if they'd been poking into all his stuff? Not just the spells he'd created or improved, but his diary and his attempts at poetry and the lists of cool nicknames he'd tried inventing for himself to make up for the things everyone else called him?

He remembered how furious he had been when he had caught Harry Potter sneaking a look at one of the most painful, humiliating memories of his life. But, when he looked back, he realised that the look on the little brat's face hadn't been jeering, but horrified. Severus realised now that, if he had read Potter's thoughts at that moment (it wasn't as though the lazy sod had made any effort at learning to shield them), they would have read, not, 'Hah! Now I know what a loser you were, and you can't frighten me!' but, 'Wait, my dad was a git like my cousin Dudley? And this is the man I've been aspiring to be like?'

It dawned on him that the boy probably hadn't had any idea what sort of memories he expected to find in the Pensieve. He wasn't malevolent, just curious and totally disrespectful of anyone else's privacy, just as Severus and Lily had been. It was part of being a child.

Was this why Purgatory was such a dreaded place, then? Because you suddenly realised what life looked like from everyone else's point of view?

On the whole, maybe it wasn't so bad to realise that he had been neither more nor less obnoxious than most of the other people he knew, apart from a few total vermin like…

He stared incredulously for a moment, and then hissed to the angel, 'What the Hell is he doing here?'

The angel followed his gaze to the small, one-handed man sitting hunched over, avoiding the gaze of everyone around him. 'Waiting to climb the mountain, presumably,' he said.

'I mean why was he allowed in?'

'For the same reason as anyone else. It might be a good idea to say hello to him, you know.'

Coming from an angel, this was clearly an instruction, not a suggestion. The first person whom I am expected to greet as an old friend has to be HIM. WHY? ANYONE else would be better. Even anyone else from that vicious pack…

Yes, but if it HAD been any of the others, you wouldn't have thought so, would you? You'd have been thinking, 'Aaargh, not HIM, I still have nightmares about him!' or, 'Ugh, not HIM, he's a psychopath who tried to feed me to a werewolf and he STILL can't understand why there was anything wrong with that!' or 'Oh, please, not HIM, he tormented me throughout my time at school AND married the woman I loved!' Any of them would seem like the worst possible outcome. So just get it over with.

Severus strode over to the smaller man until his shadow blotted out the rising sun. 'Wormtail,' he drawled. 'You finally decided to get rid of that trinket, did you? Probably the first sensible decision you've ever made.'

'Trin…?' Wormtail glanced down at the stump of his wrist. 'Oh, that. Yes.'

As he got to his feet and turned to face the taller wizard, Severus noticed that his face looked somehow different: calmer and more relaxed than Severus had ever seen him. The Dark Mark tattoo above his stump had vanished (Severus resisted the temptation to roll up his sleeve to see if his own had, too), and the bruise-marks around his throat, where his magical hand had strangled him, shone golden, like the scars of a saintly martyr.

Wormtail, a martyr? Hah!

But then, he's a Gryffindor, isn't he? They always assume that whatever they're doing is Good, because it's them doing it. Betraying a friend to the Dark Lord (not by accident as Severus had, but deliberately), murdering a streetful of Muggles just because they happened to be there, and framing another friend for the murders… if you were a Gryffindor, all was forgiven.

'Everyone's sins are forgiven,' the angel pointed out. 'Those who climb the mountain are the ones who need to understand more of what the sins they've been forgiven for actually were. But those who refuse to climb it because they don't want to find out are no less forgiven.'

'I'm not refusing, exactly,' said Wormtail, with a trace of his usual whininess in his voice. 'It's just…' He looked toward surrounding the mountain. It was cut into terraces, separated by steep expanses of sheer cliff. There was a very narrow, barely visible 'path' up to the first terrace, consisting of little more than bumps in the rock that might serve as hand- or footholds. To an experienced climber, it might perhaps have looked like a fun challenge. To a small, timid, out-of-condition, one-handed man, it was out of the question.

'I suppose you've never learnt to fly?' Severus asked.

'Y-you mean without a broom?'

'Do you see any brooms around here?'

'Uh, no.'

'Well, then.'

'N-no, I haven't. The Dark Lord never saw fit to teach me…'

'In the first place, we don't have to call him that any more. He isn't coming here – is he?' Severus added, turning to the angel. After all, considering how willing they were to let Death Eaters in, anything was possible.

'I promise you, Lord Voldemort will never be allowed in here,' the angel said. He paused for a moment, and then added, 'If Tom Riddle is willing to give up being Lord Voldemort, he will be very welcome, of course.'

'Secondly, he didn't teach me how to fly, either, and I took good care not to tell him that I already knew how to fly,' Severus continued. Lily had taught him how, when they were twelve and he had been worried that the next time Sirius Black and James Potter decided it would be funny to push him out of the Astronomy Tower window, Lupin might not try to stop them. Lily had taught herself to fly when she was nine, not because she was frightened of anything, but just because it was fun. Her son might have inherited her natural gift for it, even if he'd forgotten it once he was allowed to play with broomsticks. In that frustrating year of trying to teach the boy Occlumency, Severus remembered coming across a memory of eight-year-old Harry finding himself on top of a roof, safely out of the way of his cousin and his gang, and feeling confused about how he had got there.

Come to think of it, Severus realised, if he had actually thought about some of the memories he'd uncovered, instead of just being annoyed that the boy wasn't making more effort to learn to block him, he might have allowed himself to feel some sympathy. He ought to have accepted that he had made a lot of wrong assumptions, and that Potter Junior wasn't simply a spoilt, arrogant duplicate of Potter Senior with Lily's scornful eyes. Really, he was just another wizard kid who'd grown up in a Muggle town with a family who couldn't stand him, and who had learned to be spiky and insolent to grown-ups because it was that or turn into a frightened ball of self-doubt like Neville Longbottom.

'If you can't manage the climb, I can levitate you to the first level,' he found himself saying, before he had time to wonder why he bothered. 'And you needn't worry that I'm going to turn you upside down and strip your clothes off. I have no desire to see what you look like naked.'

'You haven't even got a wand!' Wormtail pointed out.

'I don't need one.' The two areas of magic that Severus had always found most fascinating were almost on opposite edges of the curriculum: potion-making, which worked according to logical rules, like Muggle science only with magic; and the magic that came from the wizard's mind and will, for which speaking, singing or thinking words was only a tool to focus the will. Compared with those, all the spells that just involved waving sticks and saying words in garbled Latin seemed like conjuring tricks.

'In fact, a wand wouldn't be any use here,' said the angel.

'We are wizards, you know!' said Wormtail indignantly.

'You were wizards. Just as some people here were archbishops, or judges, or cabinet ministers. Here, the distinctions between wizard and Muggle, Pure-blood and Muggle-born, Gryffindor and Slytherin, no longer exist. People don't even have nationalities or surnames here. You are simply Severus and Peter.'

'So I can't do magic?' asked Wormtail – or rather, Peter-the-no-longer-Animagus.

'Not here.'

'Will I be able to in Heaven?'

'What everyone can do in Heaven is so far beyond what anyone can do on Earth that I won't try to explain it to you now. You'll see when you get there.'

'But how am I supposed to get there if I can't climb?'

'You do what anyone else would have to do when faced with a problem they can't solve. You pray. And, as I expect neither of you has much experience of praying, I'll just explain: it's the opposite of magic. Instead of focusing on willing what you want until it happens, you focus on asking God to do whatever it is best should happen.'

Severus closed his eyes to concentrate on thinking: God, you know I hate Wormt- Peter, but I know that you wouldn't have allowed him here unless you could see something in him that is worth redeeming. So, if you are willing to let his hand regrow, or give him enough agility to manage the climb one-handed, or give me the ability to do magic, or whatever is necessary, please will you do it? Amen.

'I think your prayers are answered,' the angel said. Severus opened his eyes and saw that Peter was gone. Following the angel's pointing arm, he could see the man huddling against the cliff-face on not the first but the second up of the seven terraces before you reached the peak.

Of course – the first level was dedicated to the sin of pride, wasn't it? And a man with so little self-respect that he had spent over a decade in rat-form, so that he could enjoy the safety of being a pet instead of facing imprisonment for his crimes, could hardly be accused of that.

'Out of interest,' he asked the angel, 'what would have happened if I hadn't prayed?'

'Oh, we'd probably have kept him here for a few hundred years to think over where he went wrong. That's what we usually do, with people who didn't repent until the last minute.'

'Do you mean when they realise they're dying and worry that there might be a God, or when they realise that following the Dark wizard who is currently strangling them wasn't such a good idea?'

'Well, in Peter's case it was more the other way round. You did know that his magical hand throttled him because he refused to kill Harry Potter, don't you?'

This was one of various assorted rumours that had been floating around, and at the time Severus had been too busy with other things to worry about which version was correct. 'And refusing to murder in cold blood a teenage boy who had previously saved his life is enough to atone for all the murders he did commit?' he said.

'No, of course not. Good deeds exist for their own sake; they don't counterbalance bad deeds, any more than the way that you and Albus Dumbledore devoted your adult lives to fighting against evil, and died because of it, makes up for the mistakes either of you made when you were young and naïve. Or any more than a woman's giving her life to save her child makes up for rejecting a friend who loved her.'

'Don't you…' Severus began angrily, but the angel interrupted him with a wave of a wing.

'It's best to admit it. You're a romantic; your imagination has spaces for the archetypes of the Lady and the Mentor, and so, if the people you have assigned those roles to are harsh and unforgiving, you assume that you don't deserve forgiveness. But here, you need to learn that no-one deserves forgiveness, and everyone is forgiven. And in the meantime, Peter is up on the second level, surrounded by nobody he knows.'

'Is that the one where people's eyes are sewn shut, and the ones further off from the rock-face have to hold onto the ones who are touching it, to avoid falling off the cliff-edge?' In which case, the other people up there needed to be warned that Peter Pettigrew was a treacherous little backstabber who needed to be placed on the outermost side, so that people weren't depending on him for their safety.

'We'll make sure he doesn't pose a threat to anyone,' said the angel. 'But it isn't easy for an untrustworthy person to trust others with his safety, either. Especially a Pure-blood who has scarcely any experience of Muggles, and finds himself outside his wizarding enclave in a world where Muggles outnumber wizards by ten thousand to one.'

'Do you expect me to feel sorry for him?'

'Not if you can't manage it. But I do ask you to consider what you'd do if it were someone you cared about – Draco, for example – up there.'

Draco wasn't particularly bloodthirsty, but, remembering his confused attempts at assassination in the sixth year, it was all too easy to imagine him with a kill-list as long as Peter Pettigrew's, probably consisting mainly of random bystanders he had killed by accident. And he wouldn't cope well with isolation, either – although Draco tended to recruit henchmen who were too dim to argue with him, where Peter Pettigrew had only ever aspired to be the sidekick of the biggest bully available, starting with James Potter and Sirius Black.

And how was that different from the way you started hanging around with Avery and Mulciber?

'If Draco were up there and lonely, I'd want to be with him,' Severus said. 'But I don't imagine that Peter Pettigrew would relish my presence any more than I would his.'

'He doesn't like you, certainly. But at the moment, you're the only person he can be reasonably sure he can trust.'

'Trust me? Why? No-one else does.'

'Because when he was assigned to you as an assistant, you may have annoyed him by insulting him in front of visitors and not giving him anything more interesting to do than housework, but you didn't take advantage of your authority to hurt him, did you? You may not have treated him with any more respect than you'd show a house-elf, but – you're not the sort of person who'd mistreat house-elves, either.'

'Are you accusing me of being a nice person?'

'No. Just a more decent person than Peter. Which is why he needs you to teach him.'

'Why are we even discussing this?' Severus asked. 'I haven't served my time on the first level yet. He may not need to be purged of the sin of pride, but I do. Or doesn't my soul matter as much as a Gryffindor's?' He realised that he probably sounded as whiny as Pettigrew now, but he was past caring.

'Believe me, you matter immeasurably,' said the angel. 'You don't ever need to fear again that you are insignificant: just a child caught between warring parents, just a geeky teenager wishing he knew how to impress the girl he loves, just a pawn in an ever-more-complex game of subterfuge. You are loved by God: loved so much that if you were the only person who needed saving, he would give everything to save you alone. Don't ever forget that. And don't forget that everyone else here is loved to the same degree. Including Peter. I can take you to him now, if you're ready?'

So this was what happened in Purgatory? You didn't get a mentor, you got commandeered to be a mentor to someone so odious that he made you realise how nice by comparison all the people you'd thought you hated when you were alive were?

Yes. It would be, wouldn't it? Hell wasn't simply other people; Hell was being lonely in a crowd. Hell was where, even when you were with people who had been your best friends when you were alive, both you and they had lost all the qualities that enabled you to put up with each other. So, conversely, Heaven must be where, even when you were with the people you had hated when you were alive, both you and they had grown up into the people God had created you to be, and you could see how much there was in them to love, just as God loved them. So Purgatory had to be the process of changing from one to the other. And it was more straightforward to start with an enemy than with someone you wanted to idealise.

'Yes. I'm ready.'