Eventually

He was on his own. He knew that because Rose and Mickey were wandering around the TARDIS. Mickey had taken her away for a grand tour. Probably lost, but the Doctor knew Rose would find the way back.
Eventually.

He sat in the chair next to the console in the middle. He had his hand on his chest. Next to her letter. He didn't read it again, he didn't need to.

He first thought about the human race as a whole. About how they were always learning. About the universe. About things he took for granted. About how they always seemed scared at the physical beings which targeted their species, but how brave they were to face whatever was coming.

He thought about her. About Madame de Pompadour. How he'd promised her. And how she always waited. Always believed. How she had fallen in love with him even in those few times they'd ever met. How he'd let her down. How she died still waiting for him.

He thought of every one he'd left behind. Gwyneth in Cardiff, Sarah Jane. Even Jack passed through his mind as he listed them all off. All alone. All dead because of him. Sure, Jack might have survived, and Sarah Jane had been alive the last time he'd seen her. But they'd die too, eventually. They all did eventually. Except him. He'd live on passed them all.

He thought of the Time Lords. His people. How he'd lived passed them. How he wasn't supposed to live passed them. How he'd let them down too.

About the Daleks. How he'd lived passed them all. This thought did fill him with some sick happiness he was not proud of feeling. Happiness he'd managed to live on after them. How they'd perished because of him. Because of one small humans desire to save Him.

Rose. Sweet Rose. So set on saving him that she'd risked the whole of time to do so. And how she didn't remember doing so. He'd tell her. Eventually.

Eventually. This word stalked him just like Bad Wolf had done. Eventually he'd make sure everything was alright. Eventually he'd fix the Chameleon circuit on the TARDIS. Eventually he'd make sure that every time he travelled somewhere, they went to the right place. Eventually she, Madame de Pompadour, was going to die anyway. Eventually they were all going to die. Eventually Rose was going to leave too.

He thought of Rose. Of just Rose. Of her face, her smile, her hand in his as they'd run from something. The way she'd always trust his judgement. They way she placed everything into his hands. Her life. Her future. Her faith. And yet...

Eventually every good thing must come to an end. She'd leave him. She'd die. And he'd be on his own again. Just like he always would be. He knew this. But this time, it was different. She was different. His life would never have true meaning without her.

Eventually she would leave. Whether if it was her own choice. Or he'd become so afraid for her he'd dump her back with her mum, her chips, her 9 'til 5's. Or he didn't become afraid. She never wanted to leave. And then, she would die too. Eventually, she'd perish away. He doubt it'd be old age. He knew it was a terrible thought but he doubted with every fibre of his being that while with him, she'd live to become old. He knew then he'd take her back some day. Some day.

It was then he felt something drip off his chin onto his hand, still on his chest. He then knew that Mickey wasn't the idiot he'd thought him to be. He knew he'd taken Rose so she wouldn't be here for his ponderings. Because she held him in such a high place, he was her rock. Her faith. The reason she knew everything was going to be alright. And if she was there now, this faith would collapse. Shatter like the mirror in the Time Window.

Because, eventually, even a Time Lord needs to let everything out. The stress, the despair, the sheer longing for something worthwhile.

Because, just because, eventually, every Time Lord needs to cry.