Edinburgh, 1867:

Myrrha's love spells were not dissimilar to the amnesia spells she used to suppress love. If Robin and Jack had been more communicative, they could have compared notes. Both spells had a deadening influence. Both cut you off from parts of your mind and made your character subtly different.

To Robin, it felt like being under a mild anaesthetic. His lips were tingly and numb. His thoughts crawled through frozen corridors – and, every so often, a falling icicle would pin them to the ground and halt them altogether.

It wasn't amnesia as such. He could remember every awful thing Myrrha had ever done to him. All his memories were accessible, they were just... lit differently. That was the only way he could think of to explain it. They weren't changed in any way, they just all showed her in a good light.

He was relatively old when she first tried the love spell on him: twenty one, living with Ellini in Edinburgh, and just starting to be able to let her out of his sight. 

He wondered afterwards if Myrrha had been waiting for the moment when it would cause the most pain to Ellini, because he was relaxing his guard, and she was not trying to escape. Sometimes she reached over and touched him in the night, as if even the caresses of her tormentor were preferable to the silence in her head. Within the very specialized circumstances of Robin and Ellini's relationship, this was practically love. 

And Myrrha had chosen this time to put Robin under her spell. It couldn't be a coincidence. She was trying to torment her. The trouble was – as Robin could have told her if she'd bothered to ask – it was impossible to torment Ellini these days. Myrrha was always trying, and never getting it right. After putting Robin under her spell, she moved them both to Pandemonium, and denigrated Ellini to little more than a maid, but the girl didn't bat an eyelid.

It must have been infuriating, the way she hummed contentedly while carrying out her demeaning duties. The way she was grateful to be excluded from balls and parties. The way her rags became her better than a court dress from the House of Worth. She was like a Cinderella with no dreams. He supposed dreams weren't good for much, once you'd lived through your worst nightmare.

He and Myrrha got married on his twenty-fifth birthday – or, anyway, on the day that Myrrha had always assured him was his birthday – at St Giles's Cathedral in Edinburgh. This was on the human side of the railings that divided the city in two, so some of the wedding-guests were nervous, especially among the trappings of a Christian Church. 

But it was the most spectacular building on the Royal Mile, and so it had to be the venue for Myrrha's wedding. If a wedding was an affirmation of a woman's worth, she was not going to skimp on the details.

This grew more and more apparent as the day approached, and the ferocity of her expectations became clear. All her movements had a kind of suppressed violence. It wasn't nervousness – he had never detected a trace of that in all the years he'd known her – but a determination to enjoy herself, to look perfect, to impress everyone, that robbed her movements of all their customary grace. She was jerkily, jaggedly cheerful. And somehow she was more terrifying to Robin in this incarnation than any other. He was almost glad of the deadening influence of the love spell.

As a result, his memories of his own wedding day were a patchwork of impressions, especially when it came to recalling Myrrha. He remembered voluminous skirts and piled-up hair, a twelve-foot train, loops of pearls strung across her bare, shapely back. He remembered a globe-like rose in her bouquet that resembled a pig's heart. He remembered trees inside the cathedral, stretching right up to the ceiling and spreading their foliage across it in mockery of the fan vaulting. 

He remembered thinking how un-Myrrha-like this all was: white when she would have preferred red, staid and ceremonial when she would have preferred some desperate, life-or-death game.

In fact, he never stopped expecting it to turn into a game. The whole time, he was convinced there would be a band of brigands bursting into the church. Or he was going to lift her veil and be confronted with a fanged succubus. Or the dress would crumple to the floor as his bride dissolved into a thousand snakes.

When the ceremony was over, and the threats all failed to appear, Myrrha lifted her own veil and dropped it over his head too, so that they kissed beneath a sheer canopy in some bizarre parody of modesty. He remembered hearing mutters and giggles from the crowd – people saying things like, "Adorable creature", "How charming!" and "What a sweet child".

It was so outrageous that he almost laughed against her lips, in spite of the love spell. Good Lord, how could she get away with it? The white dress? The veil? The coy smile she gave them all as she turned away from him and swept the congregation with her gaze?

He couldn't feel sorry for her after that. She had pulled off such an audacious trick that even the strain of holding the perfect wedding seemed to leave her. He saw her cheeks glow under their paint. The most twisted woman in the world had convinced a cathedral full of watchers that she was demure – charming – virginal. 

Robin wanted to run down the aisle, seizing random guests by their lapels and shouting, 'She showed me how to cut a throat when I was ten! She brought prostitutes to my room when I was sixteen and personally supervised the loss of my virginity! I can't believe you've been taken in!'

But he didn't. The love-spell – or the cold aftertaste of her lips – slowed his reactions, and after a while he found he was more inclined to laugh than shout. 

He admired her, veiled white monstrosity that she was. If the love spell had ever achieved a love-like effect, perhaps it was then. He saw everything she was, and he admired it. She was mad, maniacal, audacious. She would go on being mad, maniacal and audacious no matter what you did. She would annihilate you and everything you cared about – the whole world, probably. She was unchangeable and unstoppable, and you might as well love her for it. For the first time, he understood that the word 'smitten' came from the word 'smite'.

After the banquet, which was tasteless and rubbery in his mouth, they were left alone together in the vestry – a small, cold room with whitewashed walls that Myrrha had transformed into her personal dressing-room. She'd had mirrors, cabinets and dressing-tables moved in here from her rooms at Pandemonium, because the performance of demure bride – the performance she was nailing – required several swift changes of costume, and there was nothing like familiar furnishings to speed the process along.

Robin watched maids bustling round her, unlacing and unpinning her, sliding bangles onto her outstretched arms, decking her as though she were a Christmas tree. When they had stripped her down to her corset and petticoats, they withdrew – presumably to fetch the next gown – and Robin was left alone with his new bride. 

She took out one of her earrings and massaged the lobe, for all the world as if she was an ordinary woman and not a criminal mastermind.

"Will you behave yourself," she said, "if I take the spell off you for a moment?"

"Yes, Mrs Crake," said Robin.

He saw her flinch at the name, but she waved her hand anyway, and the cold, crawling slowness in his head evaporated. He licked his lips to enjoy the sensation in them, the way you might stretch after a long journey in a cramped railway carriage.

"You don't like 'Mrs Crake'?" he said at last.

"I already have a name," she replied. "And it's singular enough, I think, not to require another. I'm Myrrha. It was a slave-name to begin with, but I like to think I've made it my own."

She crossed to the dresser and unlocked a tiny drawer beneath the mirror. She drew out the little glass phial she was in the habit of wearing around her neck. It always snuggled in her bosom, looking perilously fragile amid the forces that heaved her breasts up into such an arresting cleavage.

It was full of white powder – poison, he had always assumed. It had seemed odd that she never took it off, not even in bed, but then you sometimes needed to kill people at unpredictable moments, especially if you were Myrrha.

"I've never seen you take it off before," said Robin.

"It wouldn't have suited the dress."

"Why not? It's white."

She gave him an irritable smile. "My love, please don't pretend you know anything about bridal fashion. You'll make me angry."

She fastened the chain around her neck and tucked the phial into her bosom. And Robin thought: odd that she didn't let the maids do that. The maids don't know about it, it would seem.

"What is it, anyway?"

"It's a part of me," said Myrrha, locking the empty drawer behind her. "No more questions."

Robin didn't ask any. He shifted his weight, let his gaze drift, the way any young man might who was waiting around between the stages of a tedious ceremony. But he had to think very hard about each of these casual motions, not because he was excited – he'd been a prisoner for too long to be easily excited – but because everything about this moment seemed significant. The tiny vestry, with its whitewashed walls, was pressing in on him, as if desperately trying to force him to pay attention. Gram was glowing next to his ribs like a red-hot poker. 

Myrrha had never taught him magic, but she talked about it a lot, so he had been able to pick up a few basic precepts. And one of the oldest and most basic was that you did not leave parts of yourself lying around.

And she had locked the drawer behind her, even though it was now empty. And dropped the key on the table-top. And now the maids were coming back in to dress her, and she'd forgotten all about it.

He lolled around, leaning against the wall, while the maids did their work. Four of them were holding up a white gown between them, which they very carefully eased over her head. It was just like the wedding-dress, except it was surrounded by a mesh of fine silver chains, turning the gown itself into a kind of chess-board with only white squares. It chinked and jingled as she moved.

He wondered what she was trying to convey with this one. Was it a commentary on the state of marriage? Was she trying to suggest that, for all the finery, a bride was nothing but a pretty prisoner? Well, he knew what that was like.

It was not true to say that he'd never fought her. She had terrified him early and mesmerised him frequently, but he had still tried, on occasion, to push back. At Sicily, he and Gram had tried to run away – once on a steamer after getting lost among the crowds of Syracuse, and once into the tunnels under Mount Etna, which they had childishly assumed would lead them down to the demon realms, where Gram could find them shelter with his family. 

That last time, she had broken both his legs – which wouldn't have been so bad except for the way she crooned and fawned over him during the long months of his recovery.

Now she assumed he'd grown out of it. In a way, he had. After Ellini, he had come to realize that Myrrha had moulded him into his own prison. He knew what he was now – he knew how much he'd enjoyed it – so there was little sense in running away and hoping for a better life. If he was a monster, he might as well be the best monster – living in a palace and married to the Queen of all the Monsters.

He knew that. He'd been over it hundreds of times. He didn't know what he was hoping for, but perhaps that was for the best, because Myrrha could spot hope at twenty paces. She had an eye for it, the way an obsessive cleaner would have an eye for dust.

When she left the room, he stood very still, listening with his whole body, just like she'd taught him, letting the sounds weave a cocoon around him until he could use them for his own protection.

No, not yet. Footsteps, but not hers. Too slow to be a maid – Myrrha worked them hard – and too erratic to be an ordinary wedding-guest. It was Ellini.

She came in without knocking. That seemed rude for a girl who'd been so well brought-up, but he realized now that there was no precedent to judge her by. She never willingly entered a room that contained him, least of all a room that contained only him. She never tried to get his attention. Apart from anything else, she didn't need to, because she knew she always had it.

He wasn't bitter about the way things had turned out. He never could have gained Ellini's love by conventional means, not with all the patience in the world. He had her terror, and he'd had her body – and both had been pretty damn good. The thrill of hurting someone that sensitive – of terrifying someone with that good an imagination – had been the purest, darkest, most unadulterated liquor in the world. He'd been drunk on it for months. 

He just hadn't realized how frustrating it would be to have her terror but not her glitter. She tensed when he touched her – she was exquisitely aware of him – he filled her nightmares – but she had never glittered for him. That part of her was gone. At first, he'd been petulantly glad about it. If he couldn't have her love, then at least he had ensured no-one else ever would. But lately he had sensed a spark, a resurgence, in Ellini. It might take decades, he thought, but she would recover. And he knew that the day she glittered for someone else would be the worst day of his life – worse than Father Volpone, worse than Miller.

"Well," she said, in that maddeningly mild, distant voice of hers.

"Well," said Robin, still looking at the drawer.

"How does it feel to be a married man?"

He shrugged. "I have a headache, but that's probably not related." He turned to look at her, and his lips twitched into an involuntary smile.

Ellini, on this day, must have presented Myrrha with something of a problem. She didn't want her looking pretty, and diverting attention from the bride. On the other hand, she couldn't let her turn up in rags, because every aspect of the ceremony was designed to reflect favourably on Myrrha. 

The ideal solution would have been to ban her from the ceremony entirely, but Robin knew why she hadn't done that. Myrrha liked to have Ellini where she could see her, because when she couldn't see her... she couldn't see her. All the magical methods she used for spying and prognosticating – that pack of cards, the bowl of water she infused with droplets of ink – were useless when it came to Ellini. They didn't work on her. Robin had never been able to find out why.

In the end, she had handed Ellini a plain, loose-fitting gown in the style that had come to be known as 'artistic', after the pre-Raphaelite paintings that had inspired them. They were very fashionable in the rational dress movement, and Robin thought it had been a rather neat solution to support dress reform and make Ellini look frumpy at the same time.

It was shapeless and brown and had puffy sleeves. It wasn't unflattering – nothing could be unflattering on that girl's figure – but it eliminated any danger of her upstaging Myrrha on her special day.

Ellini looked quite comfortable in it. Robin thought again of his wife's hopeless torture attempts. It was funny that she was trying to punish Ellini by exiling her from the tight bodices and rib-crushing corsets that were the bane of every fashionable woman's life.

"You grew up in Sicily, didn't you?" said Ellini. "I think you told me so once. Or was that just Father Maloney?"

She raised her eyes to meet his, and Robin felt his spine tingle. This was the closest he ever came to drawing her out – when she risked eye-contact to reproach him. It was the closest she ever came to sparkling, when her eyes glinted with contempt.

"I was there from the age of ten to the age of seventeen," he said. "Why?"

"Isn't there a tradition in Sicily that you can ask the groom any favour you like on his wedding day, and he has to grant it?"

Robin felt a layer of gloom settle in his stomach. "It's the father of the bride. But go ahead."

"Oh." She fidgeted a little, poking her shoe into a crack in the paving slabs. "Well, in any case, I wanted to ask you a favour."

"I gathered that. What is it?"

"If I chose someone else to look after me – you know, because you'll be very busy now with your wife-"

"Sorry," said Robin, raising a hand to slow her down, "what does 'looking after you' entail?"

She shrugged. "That's more or less what I want you to teach him: how to keep men away from me, how to avoid riots-"

"Is that what you think I do?"

Ellini risked another glance at him. It was cold and shiny. "Whatever you do, it's very effective. I've been left in peace for a long time now. I actually think fewer people have died while I've been under your protection-" she put a sarcastic stress on the word, "than would have done if I'd never met you."

"I think you would have traded a few hundred strangers for the safety of your family," he retorted. He knew it was cruel, but Ellini didn't flinch.

"Will you teach him?"

"Why must it be a 'him'?"

She gave him another blank, contemptuous look. "I prefer 'hims'."

Robin raised a hand to his temple. His headache was worsening. He was afraid of suffering another blackout, because Gram would be in control then, and Gram couldn't be trusted around Ellini. It had always irked him that he wasn't allowed to cut her.

"Then you do intend this 'him' to be your lover?"

Ellini hesitated. Perhaps she hadn't expected him to be so direct. "I... don't know that I can have a lover," she mumbled. And then she added, in a louder voice, "Myrrha said you'd agree."

Robin turned away from her to hide his grimace. She had said it as though it had been an argument she'd been hoping not to resort to, which made it so much worse. Her kindness made him angry just as her contempt made him tingle.

How dare she hint that he was ruled over by his wife? How dare she be right about it? How dare she feel sorry for him? He was the one who was marrying someone else – he should have been feeling sorry for her!

"Myrrha spoke to you?" he said at last.

"Just this once. When she gave me my dress. She also told me to wash my hands before going into her library because she was tired of finding finger-smudges on the books."

"Huh," said Robin, because he didn't trust himself to say anything else.

There was silence for a moment, and then Ellini said softly, "Why does she let me stay?"

Robin shrugged. He had wondered the same thing himself, more than once. "She wants you where she can see you."

"Why?"

Robin changed the subject, because he didn't like to admit his ignorance. "Do you have somebody in mind? For me to teach?"

"No," she said, transferring her attention once again to the paving slabs. It was hardly an innocent gesture, but he believed her, simply because he knew how long her recovery was going to take. The way she flinched for him – well, he saw a shadow of it in every man she ever met. It must have taken a lot of soul-searching for her to admit that she preferred 'hims' because, at the moment, she shrank from them as though they had the plague.

"Can't promise I won't kill him," said Robin, with an attempt at a smile.

"Wouldn't believe you if you could," she muttered.

Nothing could have turned the attempted smile into a real smile so quickly. God, he loved it when she hated him!

"Just so we understand each other," he said, spreading his hands innocently.

"We always will, I think."

When she left, it was hard to remember about the drawer. He felt buoyant. He tried to remind himself that there was little enough to feel buoyant about – but that had always been the case, all his life, so it couldn't stop him.

It was only when he felt the heat of Gram next to his ribs that he remembered – a patient prickle, almost like a nudge.

Robin forced himself to listen. When the sounds of the Cathedral had spun their cocoon around him once again, he stepped forwards and picked up the key from the dressing-table. It was cold in his palm.

He used it to unlock the drawer, watching in the mirror for any sign that the door to the vestry was about to open. 

The drawer was empty. He had seen that it was empty. But it didn't take him long to locate what she had been trying to protect – a panel in the wood that could be pushed inwards, causing a tantalising click.

For a moment, he thought nothing had happened. But then he realized the mirror on top of the dressing-table had tilted slightly in its frame. He lifted his hand to push at it, and then suddenly remembered how telling finger-marks could be. He took off his jacket and wrapped it round his hand, and then gave the mirror a little push, causing it to swing inwards. Gram was trembling – practically vibrating – next to his ribs, but Robin knew that they were all his own tremors, and that Gram was only suffering them to keep him from making a mistake.

There was paper back there: old sheaves of paper crammed with spidery writing, clearly from the time when paper had been an expensive commodity, and every inch of it had to be made the most of.

Robin took it out with tremorless hands and read:

This day, the 28th of April, in the year of our sovereign lady Elizabeth the twenty fifth, I, Johannus Faustus, held conference with a Daemon.