The Doctor's ancient, green eyes were filled with tears once again. Amy and Rory had left him to see their new bedroom, knowing that he needed some time to himself.
Idris, or the TARDIS, was gone. He never felt the loss of his family, Gallifrey, the Time Lords, everything heavier than now. He had had the chance to talk to her, to really make her understand how much he appreciated and loved her. Every day, in every age, in every part of space, wherever they had been, and she'd never given up on him. She'd always appeared, even if it did seem hopeless.
Why hadn't he? He was listening to her, saying what she had wanted to say for 700 years, but she would never get to know, how he was feeling the same. He had listened, instead of speaking up for once. He wished he could go back in his own timeline to talk to her, and yet even if he knew it was impossible, he started imagining how the conversation would go.
His eyes were locked on Idris, making sure he saw every bit of her in her human form. Right before the lights started pulsing from her body, making her invisible to him again; he opened his mouth, lost all control and let all his feelings run away with him: The best moment of my life, was when I turned the key and we took off to our first adventure, and I can't even imagine what life – a Time Lords long life – would be without you.
Back in the TARDIS, with the low humming and the low light, he was alone when he opened his eyes again. The Doctor got up, stroked the TARDIS for the millionth time, and closed his eyes briefly. He missed talking to the TARDIS, even if they only had had a short moment together. He opened his eyes, and realized that a tear had found its way from his eye, running down his cheek. He let it stay there for a bit, making it a gesture for her. Then noise from one of the corridors, and Amy and Rory, joking appeared. The Doctor hurried to remove the single tear from his face, blinked a few times, and turned around. "Okay, who's up for some dart?" he smiled wide, but he was still thinking about Idris.
I guess, he thought, is one of the burdens of being a Time Lord. Lord of time, and yet no time for being vulnerable.