When he stood before the Beast, the first thing he felt was fear.

Choking grasping suffocating fear. Not because he was facing the devil – the ultimate evil, the devourer of souls, the torturer of innocents. Not because he knew, he knew that he would die down here, die with fire before him and the screams of Satan in his ears.

He felt fear that everything that the Universe was, everything he knew it to be – Everything it had been, is and would ever be – he feared that by the mere presence of this one creature, all existence would turn inside out and be torn to shreds, because it defied all logic, everything he had ever known to be true beyond a shadow of a doubt was being shattered by the being of this one foul monster. He had nothing. Less than nothing. He'd lost the TARDIS, Rose, his planet and now his sheer belief that this was wrong and he was right.

He had nothing.

When the fear faded he felt disgust. Loathing and burning hatred, because for all its roaring and spitting, this being was intelligent, had been intelligent, had displayed its genius for all to see. So its deeds were not the mindless, instinctive ploys of an animal. They were the twisted, calculated evil that only comes from genius. Born from a place of bitterness and anger and bile, forged in fire and hatred and the prospect of eternal damnation, it had preyed on the minds of those too weak to ignore him. It had manipulated them, teased them, played with them like a particularly vindictive cat plays with a particularly stupid mouse and then it had let them go. Let them think that they had won, that they could run, that they would be safe.

It could hear the relief rushing through them, as it let the string it held them on run gradually to the end of its girth. And then it plunged them into darkness.

The Doctor had seen things, many things, but he knew that nothing scared people, any people, more than the idea of an evil they couldn't defeat, that wouldn't stop coming, that would find them, all of them, in their beds and in their homes and it would take them one by one with no mercy.

This was evil that had turned the most innocent, harmless creatures, into the stuff of nightmares. That was worse than death. How could any human mind, even if it survived in tact, deal with the knowledge of what it had done?

And the beast knew. And the Doctor hated it.

But under all that, underneath all the loathing and disgust and the satisfaction that this creature would die, must die, beneath all that glowed tiny specks of pity.

He saw what this beast had been, what it was, what it could have been. He saw its potential.

He saw the power, tied and fettered, pulling at its restraints, champing at the bit, and he knew that feeling. He'd felt it himself, hundreds of times, hundreds of years ago, desperate to be free of rules and restrictions, wanting to see the universe, and learn, and to show it, them what he could do, what he was worth.

And he had been trapped once too, not quite like this. Exiled on a backwards little planet, unable to travel in any way but time. And he had grown restless, wanting. He had felt at times that he would have done anything to escape.

But he had not. He wondered if that was the difference between him and the beast. Perhaps, had his exile been more extreme, perhaps if it had lasted longer, then he would have been driven to these ends.

He knew he had the potential in him – the Valeyard still followed him in his shadows, waiting, watching. And he wondered – how long would he have lasted, in this hell, before he became like the monster? How long had the monster lasted? What had it been before?

A genius, driven insane by his prison? Or already insane?

The Doctor knew he was seen as the devil by some – a memorable encounter in his fourth life had shown him that. Was this what had become of the monster?

Was this what would become of him?

And then the fear clawed its way back, bringing with it the hate and the loathing, but also a desperation.

While he felt a sympathy for the devil, the Doctor would never become him.

And above it all, even above Rose, that was what he believed.