'It was merely a game to them,' whispered the Doctor.

Kristeva waved away his concern. 'Call it a rehearsal. It served our purpose.'

The Doctor noticed that the way Kristeva said 'our' was inclusive. Kristeva was continuing to draw him into the Faction, implicating him, trapping him with words and actions and emotions. Well, play the game, Doctor. "This Edifice that we're standing in when we first met, you didn't know what it was, did you?'

'We still do not; admitted Kristeva. 'No matter When we find out, we will simply go back in time and ensure that we knew all along.'

The Doctor wanted to gasp at this outrageously cavalier approach to temporal manipulation.

But instead he simply said, 'I believe it will prove to be of vital significance to ... us. Once I can access the appropriate technology on Gallifrey, I can present the Edifice to you in its entirety.'

Kristeva placed one skeletal hand on the Doctor's shoulder. It was a gesture of approval. The Doctor forced himself not to shrink away from it. 'We're pleased with you, Doctor. Though it is of less importance to us now.' The hand withdrew back into Kristeva's nightblack gown.

'All things will come to us shortly.'

The Doctor felt a pang of alarm.

'Things have moved on since Greyjan's reappearance,' continued Kristeva. 'Mother Tarra has taken charge.'

'Who is she?'

'One of our finest young recruits. If someone over a thousand years old can be described as young.' The thought seemed to amuse Kristeva greatly, and he cackled until he broke into a hacking cough. 'Does it matter who she is? She's just another of our Agents, a child to whom we made the Faction's Promise of Impossibility. She killed the real Tarra, took her place, then killed Tarra's father. He was a former High Councillor.'

The Doctor sensed the moment slipping away from him. 'Leave Tarra, Uncle Kristeva. I want to serve the Faction. Let me take charge.'

Kristeva moved his head slowly from side to side. Maybe it was to say no, maybe it was a gesture of disbelief or regret. 'You still have much to learn, Doctor. When to stay. When to leave.' He gestured through to the other corridor, where Ressadriand still stood, frozen in a moment of time. 'As you know with this Time Lord here. You know you have left him to die.'

The Doctor could feel his hearts pounding. What had he done?

'You know you can change the past, Doctor. But will you? A classic dilemma for a novitiate into Paradox. The first temptation. Save one life by changing the past. Will you stay and save him? Or will you leave? You have the Faction's licence, Doctor. Your own Promise of Impossibility.'

The Doctor looked between the huge, static spider legs to where Ressadriand remained, unaware of the danger. 'Once I make one change, I'll have crossed the Rubicon.'

'An apt metaphor,' said Kristeva. 'Like starting a war.'

'My first paradox,' whispered the Doctor. 'All the others will seem easier after that. Too easy.Where would it ever end? No!' His voice became a shout. 'It's the cheat's way of doing things.'

'Look at the boy, where you left him,' said Kristeva, pointing at Ressadriand. 'He died just before you spoke your last sentence.' Kristeva showed his rictus grin again. 'Like a sentence of death.'

'No,' said the Doctor softly.

'I think you know when to leave people, don't you, Doctor? You left that young man Fitz, for example, in a place on Earth called Geneva. That's where we first found him. Directly from that moment, he was destined to become Father Kreiner, which is what we needed. That was an early sign of your Faction nature.'

The Doctor squeezed his eyes tight, not wanting to listen any more, but knowing that he had to. 'Go on.'

'You left your friend Romana once,' continued Kristeva. 'She thinks she learned from you how to distinguish what to fight for and what to fight against. Directly from that, she started on her path to becoming President. She even invoked the right of challenge against the incumbent President, Flavia, for the first time in two hundred generations. And now her futile attempts to stay on and fight the unknown Enemy are making it possible for Faction Paradox to conquer Gallifrey. It was what we needed'.

'Conquer ...?' The Doctor's head was ringing like a bell. He wanted to deny it all. But he couldn't reveal his true feelings to Kristeva. Or was it that he believed it all anyway?

'You've left others, too.'

The Doctor shook his head angrily. 'No, you don't know that.'

'You're thinking of them now you can't hide your thoughts from me if you insist on remembering them now.'

'No!'

'Friends you left to die, companions you could return to save if only you take this first step into Paradox. Save this boy. Save all the ones you left behind. I can see them in your mind now ... Adric? Katarina? Ah ...' A sigh hissed through his thin lips. 'You can't hide your thoughts, Doctor. Yes, your own granddaughter, Susan, you left her on Earth.'

The Doctor struggled to forget, but could only remember.

Kristeva pointed at Ressadriand again. 'And now here you've left this young man, and he's going to die. What significance will that have? None yet. But now that you're a Faction agent, you can go back and make it significant.'

'Tampering with past time,' murmured the Doctor in disbelief.

'Well,' said Kristeva. 'That's your job description now.'

'I could save him only by changing the past?'

'Yes. Leave the past, and he dies. Change the past, and he lives. The choice is simple.'

'The choice is anything but simple. I'll find a third option.'

'There is none,' emphasised Kristeva wearily. 'You kill him. Or you change the past.'

The Doctor stared past the spiders. 'If he isn't dead yet -'

'You killed him when you stepped this side of the spiders. As you knew you would."

'Did I? That was just ...' The Doctor struggled for a justification, peering at the doomed Ressadriand. He could feel his eyes stinging. In the end he could only add feebly, 'That was just coincidence.'

He decided he was prepared to plead for Ressadriand's life. Yet even in that moment, he knew that that would merely mean asking Kristeva to change the past too. And that wouldn't free him from the responsibility of altering the timeline it would still have been his choice.

He turned back, ready to confront the Faction agent. 'That was just a coincidence,' he repeated insistently.

But Kristeva was already gone.

In his head, the Doctor heard him say, 'You are Faction. There is no coincidence.'

And now, back in the corridor, the Doctor could hear the spiders scuttling away into the distance, leaving the tattered corpse of Ressadriand behind them. He stumbled past the remains, anguish creasing his features.

There was barely enough of the boy left to recognise. The ivory walls and floor were spattered with gore.

The Doctor slumped against the hard bone wall of the corridor, covered his face with his hands, and began to weep. Within him he could feel his very nature altering, his priorities reordering, like a physical mutation. Like a regeneration, a fundamental change in the core of his own being.

He didn't know how long he stayed slumped down like that. He only knew that he was alerted by the sound of a TARDIS materialising nearby. He hurried towards the sound.

Compassion stood before him, eyeing her surroundings warily. 'Back here,' she said, no pleasure in her voice. 'Otherwise, I'd say how nice it was to see you, Doctor. It's a surprise, obviously.'

'There is no coincidence,' whispered the Doctor.

'What?'

'Nothing,' he told her, and gestured that she should let him in. 'I need to get to Romana.

There are things she must know.'

Chapter Thirtytwo.

Don't shoot the messenger

Kellen sat quietly in the corner of the room, watching Tarra, transfixed by the strip of black armour marring the flesh of her arm. He'd first got involved in Ressadriand's odd seance group entirely because he'd fancied her, Ressadriand's friend, the gorgeous daughter of a former High Councillor. The girl with the lustrous auburn hair, the lambent pale skin, the dark, bashful eyes, and the full, inviting red mouth. She had a fresh aura that came from being in the prime of her first incarnation. She was supposed to be the latest of a large number of Academy contemporaries that he'd seduced and abandoned. That was part of the game. All the women he'd known had understood that, he was sure.

He stared at the yellow flower that he still clutched in his hand. The six petals were crushed together, the life squeezed out of the flower in his grip. He let it drop to the floor.

There had been a time, not so very long ago, when his main ambition was to have Tarra fall for him. And he'd know that had happened when she invited him back to her place, the secure quarters in the Capitol provided for her by her father, the one place where she never took anyone else.Yet here he was at last, sitting on her bed in the comer of the main room, and it had all gone horribly wrong.

That creepy old man Kreiner was leering over her right at this moment. Kelien knew from long practice seducing women at his Academy that he had a repertoire of ways for getting rid of gooseberries. In fact, only recently, he'd given the brushoff to Eton, that wet blanket, the youngster with the old face, and made his feelings for Tarra more than plain. But he knew now that his techniques would have no effect.

Somehow, he had convinced himself that he should go along with Tana's plan and yes, it was Tarra's plan, now, not his at the Reaffirmation Ceremony. He had rationalised his own terror of disobeying as mere complicity.

Tarra had accompanied Greyjan to the podium, while Kelien had reluctantly accompanied Kreiner up the access lifts to the roof of the Panopticon, where, on Tana's signal, they had released the remembrance flowers stored in the gantries for state funerals. The more he got involved in this plan, the more Kelien realised he had lost any idea of why he was doing it.

He should have done what Fitz had done fled before they got to the Capitol.

Kellen was losing himself. And he had already lost Tana.

Father Kreiner was working with Tarra at an APCN console. Working with Mother Tarra, to be precise. Yes, that was probably what had finally convinced Kelien that he was on a hiding to nothing.

Where had it started to go wrong? thought Kelien. At what point had he realised that the girl was stringing him along for a change? She'd given all the right signals, responded to all his smart comments, tripped the matching dance steps in the usual student courtship rituals.

Rituals. Yes, she'd made all the running there, too. Persuaded him to take the lead from Ressadriand when his college friend had hesitated. That was all she'd wanted the ritual, not him. And she'd made it seem so plausible, so appropriate, absolutely the right thing, to run the joke with Greyjan. At the time, it had seemed no more shocking than the hypercubes full of obscene limericks he had sent anonymously to the college bursar.

And then there was that thing with Kaufima at the seance. How could he have convinced himself that was an accident? And he'd got caught up in their rush to get to the Panopticon.

And ...

He'd been so stupid. This was too serious, he could see that now. He could see that just by looking at Tarra's lustrous auburn hair, and knowing that, if she turned, he would see her eyes no longer bashful peering at him darkly through the ghastly skull mask that grew directly from her face, her lambent skin peeling in thin shreds at the sides.

'Can you contact the ElevenDay Parliament from here?' Kreiner was asking her. He stretched his ancient arms upwards, and Kellen could hear servo mechanisms hissing inside the limbs.

Tarra shook her head. 'No, but Mother Mathara's Faction warship relays my signal. They will be pleased to learn that you have returned to active service, Father Kreiner.'

Kreiner sighed with satisfaction. 'I am pleased, too. Though I hate skulking in this place.'

'We must leave things to Greyjan,' warned Tarra. 'Our presence would alert the Time Lords, and we are so, so close to success.'

This was the moment that Kellen made his decision. He took the six sides of a hypercube from his pocket, and swiftly assembled it. Within another minute, he had composed a short message for Lady President Romana, a terse warning about Tarra and Kreiner.

The cube was just dematerialising when he felt Kreiner's heavy glove on the back of his neck.

'Bringing the boy was a mistake,' said Kreiner, his voice a guttural threat.

Tarra smiled sadly at him. Those full red lips were smiling sadly at him, a stark contrast with the batmask that tore through the upper part of her face. 'He helped us with the flowers at the ceremony. Thank you, Kellen. You sweet boy.'

Kellen could feel Kreiner's grip increase on his neck. It was getting hard to breathe.

'We're not the only ones hiding, are we, boy?' asked Kreiner. 'I hate hiding. Almost as much as I hate Time Lords. And one Time Lord more than most. When I meet up with the Doctor again, the Time Lord who abandoned me all those millennia ago, I will twist his scrawny neck like a -'

Kellen didn't hear the rest of Kreiner's words, as the grip increased, snapped his spinal cord cleanly, and severed his head.

'Please desist from doing that,' said Romana. I do believe I shall start shrieking.'

Fitz stopped twiddling his thumbs. All right, so he couldn't play with his hands, he wasn't allowed to practise throwing his trilby on to the hat stand, and pacing up and down on the expensive carpet was forbidden because apparently it disrupted the lie of the pile. There was no beer available, lighting up was 'too, too frightful to entertain', and the Lady President was no conversationalist. He wondered briefly about a longoverdue cutting of his toenails, then decided he couldn't face having to revive Romana from a dead faint. And he wasn't entirely sure whether his socks had holes, and who needs that kind of embarrassment?

Yet Fitz knew he had to stay occupied, otherwise he'd end up thinking more. And if he started thinking, he'd remember what Kreiner had told him. How the Doctor had abandoned him in Geneva, left him to the Faction, forgotten him. Should the Doctor have done that?

Would the Doctor have intended it that way? And most of all, could the 'Doctor!' cried Romana, clearly delighted.

Fitz jolted back to the present, expecting to see the familiar green coat and trailing brown hair. Instead, he saw Romana had removed one of her long dangly earrings and was talking to it. Had she gone bonkers? Fitz's first instinct on arriving earlier had been to search for communications equipment and try to contact the Doctor. Romana had advised him that all the systems would be monitored by Timon that was what she'd have done in his place. So maybe it wasn't such a surprise to discover that she had secreted a communicator in her jewellery.

'You found my personal frequency? Ah, Nivet, of course.'

Fitz budged up tighter to Romana on the chaise longue. She stiffened perceptibly at the contact, but continued to talk with the Doctor through the earring. At least Fitz could hear what the Doctor was saying now.

'... need equipment and help to control the Edifice. This could be what you need in the need equipment and help to control the Edifice. This could be what you need in the forthcoming War with the Enemy, instead of Compassion. The Edifice could be the best defence mechanism that Gallifrey requires.'

'Or the best weapon?' From her voice, Fitz thought, the Doctor would be able to hear Romana was smiling broadly, mocking him in some way. 'However, I am a little indisposed at the moment, Doctor. Where are you?'

'I'm aboard my TARDIS.'

Fitz saw Romana contain her delighted gasp, so that the Doctor would not notice. 'The 102?'

'Well, I will be so long as Combat Elite Mali decides not to knife me to death.'

'Mali,' rapped Romana. "The Doctor is not to be harmed. So long as he is not lying to us.'

'Thanks very much,' grumbled the Doctor.