Disclaimer: I do not own Doctor Who or any of the characters from the series. :-)
A/N: Spoilers for Waters of Mars in this fic! Read at your own risk.
The TARDIS stopped.
The interior was dark, save for the brilliant shaft of light pouring through the twin windows of the blue Police Box. The doors flew open and the white light nearly blinded him. Lifting a hand to shield his eyes, he heard a familiar voice.
"Doc-tor…" a voice almost musical in quality called to him, "Doc-tor…"
The cold knot of dread clenched in his stomach. Swallowing hard he left the TARDIS to face the light. The light dimmed somewhat, allowing a clearer look at his surroundings. He wasn't sure what he expected, but Bowie Base One was definitely not it.
"Where am I?" he demanded, a hint of the old arrogance creeping into his voice.
"Outside of time," the reply came.
The Doctor turned to stare at one who appeared to be Adelaide. She wore white and radiated light. But the voice belonged to another.
"The White Guardian?" he questioned taking a step back.
"Yes," the reply came, "I brought you here."
The silence weighed heavily on the Time Lord. The Guardian seemed to be waiting for him to speak. Perhaps waiting for him to explain? Maybe to confess? It didn't happen often, but this was one time in the Doctor's life, when he couldn't think of anything to say.
Finally, the Guardian broke the quiet with a simple question, "What have you done?"
Feeling like a small child being chastised by a parent, he tried to frame an answer that would justify his actions, "I saved them. I couldn't just walk away and let them all die for no reason. I've done it before."
"But this was a fixed point in time," the Guardian reminded him gently, "And as such, you had no cause to interfere. Just because there is no longer a High Council of the Time Lords for you to answer to, does not mean that you no longer have anyone to answer to."
His hands were tight fists at his sides, and he was afraid that if he allowed them to relax that they would begin to shake uncontrollably. The realization of what he had done, of what he had become, shook him to his very core.
"I take that to mean that you've brought me here to answer to you."
"Not this time, Doctor," the Guardian with the appearance of Adelaide smiled slightly, but then turned serious, "I brought you here as a reminder, and to tell you that there are consequences to your actions. You will be the one to face them. The Laws of Time were set in place for a reason, Doctor. And that is one rule that you don't break."
The Guardian had stood there, unmoving, the entire time. Just… stood there, looking like the woman who had been forced to take her own life, because he had gone too far. It was unnerving to say the least.
In the face of his silence, the Guardian continued, "You have done much good Doctor, but you have the capacity to do even more harm. You know this, and it is up to you to make sure that the choices you make, and the actions you take are the right ones. You are not as all-knowing and powerful as you might think, Doctor. There are forces greater than yourself in this universe. Do try to keep that in mind. Farewell Doctor."
The White Guardian faded away, and in a flash of light, the Doctor found himself back in the TARDIS and once again on his way. Left alone to ponder the things that made him quite sure that his end was near. The question was, how near?