He found Robin at the lodging-house on Headington Hill. His room there looked a bit like a monk's cell – narrow and sparse, with a small window, and a crucifix nailed to the wall. But Robin seemed right at home. More than at home. He had a way of spreading out to fill all the available space in a room. He was doing it now, sprawling in his chair, with his legs wide apart, trying to look as languid and offensive as possible.

Jack usually found it infuriating, but not today. He was still so numb and distant. He felt as though his mind was working through some conundrum without telling him what it was. He wasn't even sure he'd know about it when the solution was reached. He certainly wouldn't know how he'd got there.

Robin gave him that slow, spreading smile, as if he was getting funnier and funnier the longer he stood there. Finally, he said, "I'd like to think you worked it out before Danvers finished the head-count. But too late for it to do you any good, of course."

"Mary Stryde," said Jack tonelessly.

"It's better than you think. I knew her in London, when Ellie and I were living as a married couple in Lambeth. She sent me reports about the master's activities, ensured his spies were always on the wrong track. Ellie never knew she was being hunted."

For some reason, Jack could only look at the sparkling pattern of raindrops on the windowpane. Water was leaking in and pooling on the sill. "And you told her to come to the Academy?" he prompted.

"Only after you invited her. I thought it was too good an opportunity to miss."

"It's a shame," said Jack. "I liked her."

"Don't take it to heart, golden boy. Many a nicer girl has fallen under my spell. Besides, she was strapped for cash."

Now the water was spilling off the windowsill and onto the floor, with an arrhythmical drip-drip. It seemed very loud to Jack. He wondered that Robin wasn't looking at it. "Someone could have been killed," he ventured.

Robin smirked. "It wouldn't've been my Ellie. I taught her too well. Of course, she made me suffer a bit. For a while, I really thought she was going to let her love for the girls overcome her survival instincts. And there's always the suspicion, when she's being beaten up, that she's secretly enjoying it. But I knew she'd come out on top. She always does, these days."

He seemed to put a lot of stress on those last two words. But Jack was feeling too distant to be provoked. "Did you do all this just to get rid of Elliott?" he demanded. "Or was it to hurt her? She was your only friend in the entire world – you know that, don't you?"

Robin's jaw tightened. "Friend? What's that? You know what that word has come down to for me, golden boy? You know what 'friend' means to me now? It means 'someone who will tolerate me'."

"But you're so intolerable!" Jack protested. "You don't realize how impressive that is!"

"I do realize!" he said, raising his voice for the first time since Jack had entered the room. "I just want more. Is that so hard to understand? You and I were raised to be ambitious. I want to be like a normal person-"

"Then start acting like one!" Jack shouted.

For a moment, they stared at each other. Then Robin raised a hand to his forehead and gave him that new smile – so close to the old one, but so different. Full of mockery and self-hatred.

"It's too late," he said. "You know that, don't you? You and I will never be like normal people. In any case, I wanted her to more than tolerate me. Didn't care if it was love or hatred. I just wanted a reaction from her."

He was baring his teeth as he said this. His hands were clenched on the arms of the chair as if he was trying to steady himself – as if the floor was lurching.

Jack shook his head. "You're really down to your last options if you're trying to appeal to my sympathy."

Robin laughed. He took his hands from the chair-arms and let them fall into his lap. He was all ease and friendliness now, as if the previous conversation had never happened. "What was it like? That night with Ellini?"

Jack's fingers curled a little, but he didn't react in any other way. "You don't deserve to hear about it." He hesitated a moment, because this was not something he even liked to allude to, let alone talk about. "Anyway, you know what it's like. When you took her – when you left me in the church that night..."

"Nope," said Robin, twisting sideways and putting his feet up on the arm of the chair. "Never had her. Never even once. Oh, the pure, physical motion was something we went through a few times, but she was never really there."

He licked his lips, watching Jack carefully. "You had to suffer it too, I think. You know what I'm talking about. When she's like a rag-doll in your arms. When her eyes are open, but not looking at you – fixed on something an inch to the left of your ear, maybe, or just serenely out of focus. I tried all kinds of things to overcome that distance – shouting, cajoling, pain. Usually people snap right back to the present if they're in pain, but not this girl. I think it reminds her too much of Camden Town."

Jack was reminded of Elsie's plan to bring Ellini back to the present – her peculiar insistence that this was all that would be needed to make her invincible.

"What was it like?" Robin repeated. There was an extra bite to his voice now. "What was it like when you finally managed to coax her out of herself? Did it take a long time? And was it alarming, the first time it happened? Did you see her looking at you, with her soul right at the forefront of her eyes, and think, 'Bloody hell, I'd better up my game a bit, she's actually there'?"

"As we previously discussed," said Jack, his voice echoing in his hollow chest. "You don't deserve to hear about it."

All he could think was that he was so lucky to be numb. Hearing about this – about Robin and Ellini together – and, yes, it was somehow worse that she had been like a rag-doll in his arms, because it implied that he'd forced her. Of course, Jack had always known he'd forced her. He just hadn't wanted to think about it before.

He thought of her retreating into her head when that bastard put his hands on her, and it made him want to tear his throat out with his teeth. He could see it all in his mind's eye, but he didn't move. It was easy to control himself in this state, but god knew what would happen when he finally solved his conundrum, and his mind clicked back into place.

"You're not going to tell her about me and Mary, are you?" said Robin. He was smiling – as though he'd been sidling in on Jack's thoughts – but there was something a little uncertain about him. Perhaps he had expected Jack to think all those things, but hadn't expected him to keep his temper. Somehow, certainly, things were not going to plan.

"You're not going to tell her, because you know she's going to Edinburgh anyway, and you think her chances of survival will be slightly higher if she goes with me."

"I don't know that," said Jack, in a leaden voice.

"I didn't say you knew it, I said you thought it."

"I don't know that I even think it," said Jack.

"Do you think I'm going to betray her, then?"

Jack shook his head slightly, as if trying to wake himself up. "It doesn't matter. She's too clever for you."

He was approaching the end of his conundrum, he was sure of it. There was something there – something in what he'd just said.

Robin raised his eyebrows. "She has her blind-spots, though. Just like you."

Jack leaned forwards – and, as he did so, toppled into certainty. He knew now what he was feeling: coolly, murderously confident.

He had seen her with the smoke at her back, and her hair draped over one shoulder like a python. And, for some reason, the memory looked a certain way in his mind. He saw it in the colours of stained glass: the green was too green, her crimson-dipped sleeve was a deep, martyr-blood red. And the whole image was shot through with light. It wasn't just stained glass, but stained glass with the sun shining through from the other side, lighting him up with certainty.

It was, in short, an epiphany.

He let his own, slow, disconcerting smile spread across his face, let the confidence creep into every corner until he was glowing with it.

"You keep saying I'm always winning," he said. "You keep saying I'm better than you, without ever seeming to realize what it means. So let me break it down for you. There's nothing you can do that I can't undo. There's nothing you can break that I can't fix, not even people. I'm bringing her back, Robin. I'm bringing it all back. Your crimes are going to get up and walk like corpses on the day of judgement. And you'll see her at the forefront of her eyes just once in your miserable life. Right before she fucking kills you."

Robin seemed to stagger backwards in his chair. He tried to smile, tried to laugh. He said, "Golden boy, is it my birthday?"

Jack shook his head slowly. "Not yet. Very, very soon. Get ready."

***

It had taken a while for all the things he knew to sort themselves into place. There were things he had known separately which made a new kind of sense on being joined together. The fact that Ellini wasn't easy to kill, coupled with the fact that he could now see Robin as nothing more than a sad, stabby pervert, meant that she would come out of Edinburgh alive.

Logic could never have made him decide this – experience couldn't have made him decide it. Every rational argument told him that, in going after Myrrha, she was going to her death. Robin would betray her – he'd have no choice – and Myrrha clearly meant to lure her there. That was why she had let her associates fall, one after the other, at Ellini's feet, like a trail of breadcrumbs leading her to Edinburgh.

But he had seen Ellini with the smoke at her back. And now he wasn't being guided by logic, but by faith.

Still, he reined it in – he qualified it – because he was mistrustful by nature, and the experience of the past seven months made it impossible to be complacent. 

This faith in Ellini wasn't the answer, but it was a step on the way to the answer. If he accepted the idea that she could do it, his next move became clearer. Elsie's stupidly confident schemes began to seem less stupid.

He would strengthen her. Somehow, he would find the ring, the sister, and... the other one. He would drag her out of the past and into the present and let her mete out the justice that he was burning to dispense himself.

This – and the memory of Robin staggering back from the force of his words – lightened his footsteps on the way back to the Faculty. 

He was lit up with the stained-glass glow of trust, and the dimmer – but no less satisfying – glow of petty triumph. Robin had been afraid. It was going to be so sweet when he had to look Sita in the eyes again – when he finally had to face up to what he'd done.

Jack was whistling by the time he got back to the Faculty, to find Sergei on the steps, waiting for him.

"So there you are," he said, in the tone of the olden days – as though he'd had one of Jack's rejected lovers battering on the door all morning, and was tired of pretending he didn't know him. "I understood you were just staying until you'd recovered from your injuries. I didn't think you would be moving furniture in."

"What furniture?" said Jack.

"There's a man here with your piano. He says he'd take it as a personal favour if you didn't require it to be transported to the second or third floor."

"I don't – have a piano," said Jack, in a small voice. A horrible picture was starting to form before his eyes.

"Well, the work order is here," said Sergei, waving a piece of paper at him. "From some American at the Turl Street Music Rooms? He says he's leaving the country and doesn't have a use for it anymore. He seemed to think you would."

Jack shook his head frantically. "Send it back." He didn't want to live in the same house as a piano – especially not that piano. He didn't want to feel the weight of its expectation. "Send it back, Sergei," he repeated, almost pleadingly. "You know I don't play."

"Perhaps you could explain that to him yourself?" said Sergei. "Only he'll be boarding the steamer for New York by now, so I suggest you take the hint and the piano. I assure you, this carrier is not going to want to move it twice."