A/N: This is my first fanfic, English is not my native language and I do not have a beta. However, I am not using these as excuses for any mistakes and OOCness. If you see any grammar, spelling, etc. Mistakes, please tell me and I will correct them. I strongly suspect my use of tenses is a bit off, but since I don't have a beta...
Anyway, please read, enjoy, and review.

Disclaimer: Doctor Who is property of the BBC and those involved in the program's creation (like R.T.D.). The only thing I own is this story, and I am not making profit out of it.

The Doctor watched Martha go, only a little of the inner turmoil he was experiencing showing on his face. There was sadness at her leaving, of course, but also immense pride and affection. She was a great companion and she did indeed save the world. Humans never ceased to amaze him. Somehow, they could be egotistical, callous, cruel and heartless –he thought of the Toclafane with a shudder- but brilliant, compassionate, self-sacrificing and loving at the same time. A race of heroes and villains. None of the other races the Doctor had ever met could be so versatile, so different in personality. None of the other races were as good at surviving, either. He had seen ample proof of that at the end of the universe.

The Doctor frowned slightly, as thinking of the Utopia project made him think of the Master again and the terrible emptiness in his head that meant that once again, he was alone. Now that Martha had left, he was physically alone too.

Over the course of the months, he had found that loneliness was especially hard to bear in this body. This particular regeneration liked to talk. A lot. And talking to yourself, even if it isn't really a sign of madness as most humans think it to be, isn't half as fun as having someone to talk to. Particularly if he was spouting off some space-time theory he knew his human companions couldn't possibly comprehend. It was his guilty pleasure, seeing their completely befuddled expression whilst listening to the stream of jargon coming out of his mouth. Despite himself, his lip twitched, inching towards a smile. Absolutely priceless. Especially Rose's expression, the poor girl. Went completely over her head.

His half-smile disappeared completely at the thought of Rose, and consequently her and Martha's absence. He even thought of Sarah Jane, whom he had recently met again and of Romana and Adric, whom he would never see again. Those thoughts triggered the mental equivalent of an avalanche. His mind assaulted him with the faces of his ex-companions. The people who had travelled with him, kept him company, helped him save many worlds and exasperated him with their ignorance and sometimes outright stupidity and their persistence to ignore the One Rule that said that it was absolutely forbidden to wander off on their own when he had told them specifically not to go anywhere. That was simply asking for trouble, and if experience is any judge, usually they were already in enough trouble to begin with. But no matter what, they were still or had been his friends. Every time one of them leaves he goes through the same process in his mind, that of recalling all his previous companions. Of course, he was more attached to some than others, but it always stings a little. Particularly now, when he is well and truly alone.

Before the Time War, he could always go to his home planet, if he wanted to. He could've even been President, had he wanted to be, for they had offered him the job twice. He most certainly hadn't wanted it and for the most time had avoided an encounter with his people; but just knowing that Gallifrey was there and that he could see other Time Lords if he wished to, that they were in the back of his mind -silent but ever present-, was enough. Now there was nothing. Perhaps that is the reason why this regeneration likes to talk so much. To fill up that void. And perhaps that is why he got so dangerously attached to Rose. In hindsight he was immensely relieved that Rose never confronted him about that. Not until the very end, when it didn't seem to matter anymore. Maybe she had understood on a subconscious level (after all, he had never actually talked about the War) that he desperately needed someone, anyone, to drive the emptiness and the guilt away or at least to keep it at bay for a while. Rose had been more than just anyone. She had filled a small part of the hole that was left when his people disappeared from time and space and for that he was extremely grateful. But he knew that he had to let go of her eventually, as with every human who travels with him. She did confront him about that, and though she had looked hurt at his admitting that he had had a lot of female companions and that he couldn't spend the rest of his life with her, he thought she had understood.

When Martha came he felt more centered, more balanced, more on his guard. He wouldn't let that happen again. The people who travelled with him were his friends, nothing more, nothing less. It wouldn't do to depend on them too much. Sometimes he felt that it would be better to travel alone permanently. It would at least eliminate the possibility of a hostage situation. No, no, that wasn't true. If someone wanted to use a hostage against him, a nameless inhabitant of a random planet would work just as well. Almost as well. Maybe several inhabitants. Like a village. It depended on the situation itself, really, and what was at stake. That is not to say that one life is, essentially, worth more than the other, but ethics are relative, really, because anyone would chose to save a child rather than an adult, and...

The doctor paused for a second. Babbling in his head now. Worse, going of on a tangent. Really, this regeneration...

He gathered his thoughts, though he hadn't really forgotten what he was originally thinking about. His friends. Martha. Gone. He supposed the Time War changed him even more than he thought it did, because he used to handle loneliness pretty well. He was a 900-year-old Time Lord after all, and had spent many decades with only his TARDIS as company. He supposed it was the combination of loneliness, emptiness and weariness. Maybe he was getting too old for all this.

Or not. The doctor snapped out of his reverie and studied the TARDIS controls for a minute before deciding on a destination and setting the coordinates. As he felt the TARDIS dematerialise and felt the accompanying thrill he always got when going somewhere new and exciting, he knew that his wanderings through time and space were not over yet. Anyway, if he stopped, he'd have to settle down. He didn't do domestic, thank you very much. He'd just have to find a new companion soon and...

His thought process was (rudely) interrupted by what appeared to be a ship ramming through part of the TARDIS. As the Doctor picked himself up and read the name of the offending ship in question with a completely flabbergasted look on his face, he made a mental note in the back of his mind to have a word with the TARDIS later about letting strange objects (and people) in. Right now, it seemed trouble had found him again. Some things never change, with or without a companion.