Author's note : I really would love some feedback since I'm not sure about this at all. I didn't write it as a Castiel/Doctor but you can read it that way. Mentions of Destiel.
Demons Run :
He knew he had loved and been loved, there was no questioning it. But the Doctor also knew the haunted look on the man's face, the tension between the shoulder blades, the bowed head, the dead eyes. Castiel didn't think he deserved to be here. Castiel was just like the Doctor : he was powerful, and big, and mighty, and in the end, he had lost it all.
The creature the Doctor hated the most in the whole universe was himself. The creature Castiel hated the most in the whole universe was himself. They were two broken pieces who could never be functional again, and yet, as he looked at the blue eyes and saw the ghost of a smile on Castiel's lips, he hoped he could help him find himself again, and maybe, just maybe, it would be fine once again.
(Two pieces could make a whole)
Because Castiel was no man. He was a creature of wonder, who left the Doctor with eyes so bright they seemed to shine like nothing else in the world. Castiel could be the companion who would stay longer than any other.
(Two broken pieces as old as time)
He had touched him and he had seen the violence, the pain, the blood and the harsh words. Castiel was tired, had been for a while, now. He was to blame, yes.
But what of this Dean ?
What of Sam ?
What of the humans who thought Castiel was expendable ?
(He tried not to think about all the people he had left behind)
Some would say it was easier to blame the people Castiel had disappointed. Well, it wasn't, because Castiel wouldn't let him.
Castiel would think he had to die.
(It hurt because the Doctor thought about it too, sometimes)
The Doctor had seen it all and remembered every crack in Castiel's heart ; when he closed his eyes the pure heart made of glass would slowly, with a cry of agony, be shattered, and red lines of blood would appear on its precious surface. That was Castiel's heart. And at the center of this heart was Dean Winchester the Righteous Man, and Castiel had disappointed him so much he had left him behind.
(The Doctor was luckier ; he had two hearts – but that didn't mean it was more difficult to break them)
The world was a shade of right and wrong. There is a point in your life when you lose all perception of this, when all that matters is to fight for your life and your beliefs.
(When Donna had stepped out of the Tardis with another version of himself next to her and a part of himself in her, he knew what would eventually happen and yet he was glad, because it served his cause, because that was what was important – and now at night the tears on her face would not let him go)
Castiel's eyes were pleading and the Doctor drowned into him.
And he saw.
He felt.
He saw the fire and felt the pain. And as he went further and further he understood he was Castiel as the angel gripped what had been Dean Winchester once, and built him again, and loved him again, and climbed, climbed, until Dean was safe – and creatures would grip Castiel and try to take him down, again, and again, but the mission was more important, Dean was more important. Dean was loved and Castiel took every emotion, every memory, every drop of blood, every piece of soul so he could be born again.
He remembered how Donna had saved him the same way, when he had been falling again and again, drowned in his own rage, the Lonely God, when he had watched as the giant red spider was falling down with her children, with a whole race, and Donna had reached for him, and everything was better, then.
He saw the look in Dean's eyes and felt something stir in his heart when Dean tried to stab him, and Castiel's voice – his voice – was harsh when he/they spoke. When they say they had gripped his soul and got him out of hell. He knew Dean didn't understand. He felt empty when he understood he probably would never get the meaning of this sentence. Dean never caught the words hanging in the air. Yours and yours only.
He remembered the look of betrayal on Rose's face when he became the tenth version of himself. He had tried to explain he was still the Doctor, he still loved her. Hers and hers only.
Castiel blinked and it was over.
Don't blink. Blink and you're dead.
(Rory and Amy, laughing, growing old together, appeared in his mind, and the Weeping Angels came and the guilt was unbearable)
"We're two ghosts haunted by their own ghosts."
Castiel's words rang like a bomb in his ears, deafened him, took him down and yet kept him alive so he could remember all his mistakes and all the guilt he was not strong enough to bear on his shoulders. It seemed lighter, though, because he knew Castiel had seen what he had seen ; because even though their guilt was as big as the universe it was all about the two of them now.
(The sweetness of the idea still had a bitter taste, though)
He remembered Rory the centurion, the boy who waited, and the fight.
"Demons run, when a good man goes to war."
Castiel put his hand on the top of his and he heard Dean is the righteous man and their thoughts were so tangled he didn't know where he ended and where Castiel began. Their voices joined as they told the poem of Demons Run, because Castiel knew it, because they were one, suddenly, and what the Doctor knew, Castiel knew, and what Castiel knew, the Doctor knew too and it felt so big and almost too much, all of this knowledge and this eternity.
Castiel knew all about the wrath, and the fury of the Last Timelord, and he thought This is what happens when you travel alone for too long and Amy's face was here, almost with them, as if he could touch it.
He felt his own rage but there was something else, and Castiel said :
"I don't understand. I don't know what to do with them."
Emotions, the word was left unsaid, but they were together and they knew and the Doctor had a feeling that even though they stopped touching, even though they never touched again, they would still know all about each other, they would know what to do.
They would know where it hurt.
They were each other's solace and doom.
The Doctor could never be Dean and Sam.
Castiel could never be the companions he had lost.
oOo
"Night will fall and drown the sun"
Castiel put his hand on the Doctor's hand, and the Doctor saw it again : as a giant ship, the darkness took Balthazar away. It was the end, not only of the universe, but of everything. I loved him. I loved them all. Castiel had raised his hands towards Dean Winchester who hadn't even turned back to look at him and it had been over. The Doctor watched Rose being taken away from him. He had walked next to Donna and she had ignored him because she didn't remember. Amy and Rory – makeitstop.
One year, one year since the Doctor had reached for Castiel, to pull him out of the darkness. One year later and the burden was still the same – saving the world, and the universe, and saving life.
Sometimes keeping going was almost too much but Castiel – who could have fled and gone back to Dean and begged because he could vanish just like that and because he loved Dean and he wouldn't put anything before this love – never left his side and the Doctor was glad.
At the end of the world, Castiel trusted the Doctor with what remained of his life. He Castiel liked to think the Doctor trusted him too.
I do, the Doctor thought. And he knew, even though they weren't touching anymore, even though they were not looking at each other, Castiel could hear him.
oOo
"You know what happens ...When a good man goes to war."
The smiled on Castiel's face faded and he wondered why he was the angel and yet it was the Doctor who had fallen. He knew why, though : the question had been asked. Doctor Who ? DoctorWho ? DoctorWhoDoctorWhoDoctorWhoD octorWhoDoctorWhoDoctorWhoDo ctorWhoDoctorWho ?
Geronimo, Castiel thought as the Doctor touched him one last time.
"Make it happen, Castiel. Make it so it doesn't happen. Make it so I remember."
So when the Eleventh Doctor started his regeneration, Castiel left. He went back in time, because he could.
He met the First Doctor on a beach. The First Doctor was quite old, already. The First Doctor was already falling, Castiel could feel it – the harshness of the Time War would never leave him in peace.
He remembered the bow tie and he knew it would all lead to the moment when the Doctor would be crushed on the floor, begging for Castiel to come back, and Castiel would leave and have the adventures of eleven lifetimes with him. And if the Doctor had believed it wasn't possible, well – screw him.
oOo
He met Nine the day Dean Winchester was born. That's when everything changed. His other self – Cas – was hearing, from up there, the first screams of the Righteous Man.
But the true Castiel – the right Castiel – was traveling with a man with strange ears and a leather jacket.
(And if Castiel wanted to go and look into Dean's eyes for the last time, he never mentioned it)
"Friendship dies and true love lies", the Doctor muttered, and for a moment, Castiel sensed he knew all about it, but Nine was not Eleven.
And yet he had felt, as he traveled with the Doctor(s), the bond was more and more perceptible. As if it were always meant to be. He didn't understand what it was, nor where it would lead, but it was, and that was enough for him.
The day Dean was born was the day Castiel started talking to the TARDIS – or perhaps, the day the TARDIS decided to bond with him. They weren't talking, per say, but Castiel would be flooded with sensations and emotions and the Doctor said :
"What is it about you ?"
A few years later, the met Rose and Castiel remembered what true love felt like when he saw the Doctor lock eyes with her. He would have been haunted by the faces of Balthazar, and Dean, and all those he had left behind and who had left him behind, if it weren't for the TARDIS.
The Doctor asked again What is it about you ?
And as they watched the stars burn, Castiel heard something he had not heard in years. In centuries. Dean's voice was yelling Cas at the sky as if he knew there was something wrong with Cas, but he wasn't Cas anymore, he was Castiel, so he let it go.
(It hurt, but that was okay)
That night, Balthazar whispered to his ear :
"Do you think I wouldn't feel there are two Castiel in the universe : I know you, Castiel. I believe Gabriel told your little boyfriend. Just so you know, I haven't met him yet."
Castiel knew. Castiel always knew what was happening to Dean and Sam. That was his own curse : he would see everything, and strangely enough, most of everything was related to Dean and Sam. When the sun rose, a few words lingered in his mind.
I get it, you know. I won't look for you. I missed you, Castiel.
He knew at this point there was no way he would see Balthazar again. That was something of a fixed point in history – hearing this in his head, the TARDIS wrapped him in a wave of delicious heat. Castiel's heart started beating again.
(And he was glad, and a bit stunned, because Balthazar was not one to say I miss you and there was something so foreign and heart-breaking about it it should have destroyed the remaining piece that held Castiel together but no, that was okay, he had said his goodbyes)
oOo
Night will fall and the dark will rise, he thought.
"You're going to leave," he told the Doctor, and that was not a question because the Doctor knew. He always knew.
He let them be, for a while, Rose and him. He let them say goodbye properly. The last words of the Doctor for him were :
"I know what it is about you, now."
It puzzled Castiel, because he himself didn't know.
Every time the Doctor died, it hurt. And every time he was reborn, it was a wonder and Castiel would not have traded it for the whole world.
(When the Doctor picked up a trench-coat he said that was because he liked it on Castiel)
oOo
Rose often looked at Castiel, and she understood. There was something in his eyes, something in the way his touch lingered on the Doctor's arm, in the way the TARDIS would be a little brighter when Castiel was around, that made her understand he had known them longer than it is possible to know someone.
She had seen it all – the inside of the TARDIS. She knew. She loved Castiel for being here, but she would never dare saying it.
After all, she knew.
"I will have to do something terrible" Castiel told her.
(But it seemed okay)
"You're a good man, Castiel."
He thought about Dean and the TARDIS said "Don't."
He listened.
Instead, he thought :
When a good man goes to war.
And as he thought, it hit him that something was coming, something big, and he didn't know what.
oOo
"We're at the last verse, now."
"The last verse ?"
Martha was him. Martha was the girl who could have been so much more but she wasn't what the Doctor knew he needed.
He hadn't been what Dean knew he needed.
He told the Doctor not to make the same mistake. He told him not to let her think she wasn't needed because she would end up believing in it. And he listened, because there was something about Castiel, because he had always been around and he would always be.
Up in the sky, God was missing. The Apocalypse was near. Castiel would not have any part in it. Cas would.
(The end was near, but not the one he had been concerned about before)
Demons run, but count the cost" Martha said.
"Excuse-me ?"
"I didn't say anything."
That was her last words to him.
So it had started. He still didn't know what it was.
(It was almost time, now)
oOo
There had been Donna, then.
(The most important woman in the universe)
Brilliant Donna, Amazing Donna. When the Doctor lost her, when they lost her, Castiel knew it was all over.
Castiel had loved Donna more than he would never understand. He had kept count, though. Ten. Eleven was coming. He didn't go with the Doctor, simply touched him one last time and told him to remember. There had been so many things he had loved about Ten. They had walked the earth, the two of them – The Doctor and the Angel. A legend made of stars and he knew, now, he kew wht was to come.
He left the Doctor for the first time in decades.
There is a rule in the universe : you cannot be where you are already. The Doctor can never come back in time and go exactly to the place where he already is. That would create a paradox.
The Doctor was going to lose Amy and Rory and River and he was going to look at Castiel and think "I'm going to save him." But if Cas didn't go in Purgatory in the first place, that would never happen. If Cas didn't go there, Castiel could stay with the Doctor, or at least cherish the moments he had had with him – eleven lives. Cas was with Sam and Dean when it happened – Castiel flew, from behind, and the blade smoothly entered Cas's neck and there was blood.
(Killing himself didn't hurt)
He was a child of the Lord. Cas's body fell to the ground and Castiel locked eyes with Dean one last time. You cannot live if you have killed the past version of yourself. So Castiel's body vanished into thin air.
He realized, then, that he hadn't thought about his Father in years.
(The battle's won, but the child is lost)
oOo
The Twelfth Doctor rose and remembered. The strain of thoughts inside his mind was overwhelming, all the memories of a being who had been many beings, and of a being who had lived too long.
The first time he had touched Castiel, he had known – but what was the first time ? Was it when he took his hand to grab him out of Purgatory ? When he was still the First ?
He caressed the TARDIS's console and the TARDIS muttered words of love to him. He looked at himself in the mirror and took in the bluest eyes he had ever seen, the slightly muffled hair, the frown that never really left, and the trench-coat (again).
Castiel had always been the Doctor.
Time Lords have two hearts because they are two.
The TARDIS flew away and a few years back, Chuck suddenly wrote
Demons run when a good man goes to war
Night will fall and drown the sun
When a good man goes to war
Friendship dies and true love lies
Night will fall and the dark will rise
When a good man goes to war
Demons run but count the cost
The battle's won, but the child is lost.