Disclaimer: I own nothing. BBC owns Doctor Who. And I think James Patterson owns Daniel X…not really sure about that one.

Author's note: I've only read the first book of Daniel X, so all the information about Daniel is based off of that book. And basically this takes place sometime in 2008 (when the first book was published). And on the Doctor Who timeline, it takes place between 'Voyage of the Damned' and 'Partners in Crime.' So yes, the Doctor is alone (I just find it easier to write crossovers that way).

It was a sunny afternoon when I was walking down the streets of London, chewing some newly bought bubble gum and listening to my iPod. I was enjoying the normalcy of it all as the crowd moved around me like the tide of a river. Just for a moment I imagined I was a normal 15 year old on his way to meet up with some friends, instead of an alien on his way to bash-up another alien who was number 13 on The List. Sadly, my reverie of normalcy was broken when someone knocked into me.

"Oh, sorry. Really sorry. In bit of a hurry. Sorry," said the man who bumped into me as he rushed away in the opposite direction.

I looked back and as I watched the man disappear, his long trench coat bellowing out behind him like a cape, I got a weird feeling picked up by my sixth sense. But before I could figure out what the feeling meant, it was gone just as fast as the man. Strange…I thought as I began to wonder who that man was.

I quickly stopped it though. I didn't have time to waste so I could ponder the weirdness of that dude in the trench coat. I had to prepare for number 13…lucky number 13…

"You will not destroy me, Daniel X! You are not the first to try!" taunted number 13.

Number 13 was a snake like creature that could fit itself into any sized pipe, making it so that it could basically move anywhere. You see his species can't take the ultra-violet light that the sun gives off, so it slithers around in the pipes until night when it would come out and feed off people's brain waves until there were none left, making them useless to the world and better off dead.

Now normally this troublesome snake-y wouldn't have been so high on the list if it wasn't determined to go after the smartest people on the planet. Higher IQ equals more brain waves, which equals more food, and snake-y was as greedy as a fat man at a buffet. It had already taken out at least two people that could've been the next Albert Einsteins, a child prodigy in Germany and another in Algeria. Right now it was heading after the creator of the ATMOS device, but I wasn't going to let him get that far. This going to end here…If only I could get him out of those damn pipes!

"Yum…I can just smell those delicious brain waves…Your making my mouth water, Daniel," hissed number 13 through the pipe, sounding like the wind whispering through dead leaves.

"Well, how 'bout you come and get some," I retorted, hoping that will lead snake-y out into the open.

We were in the basement of London's Water Works. The basement consisted of long mazing concrete corridors, with leaky pipes lining the ceiling and parts of the walls. The whole place was underground, and these pipes connected to sewers and the water systems of almost every building in London. It was from here that they controlled the water when it couldn't be controlled from its building above, which sat near the water processing plant. But I didn't really care about the technical use for the place. It could've been the pyramids of Egypt, for all it mattered to me. All that was important now was getting to number 13.

"Nice try. But I won't do it…though you are very tempting…," said snake-y.

"What are you on a diet? Are you getting fat from eating so many geniuses?" I taunted, trying to find out which pipe snake-y was in.

My slow and measured footsteps echoed against the damp walls of the dim corridor. Somewhere off in the distance drips could be heard as a few pipes gradually wasted gallons and gallons of water. Other than the sound of my breath, there was nothing else. Everything was completely silent.

"No…I'm saving myself for someone else…but you can be dessert…" number 13 whispered.

Using my ears more than my eyes in lack of light, I could almost place the source of its voice. I side stepped over to the right, going as slow as I've ever gone in my life, not wanted snake-y to think I was catching on to his location. If I couldn't talk him out of the pipe, I could just take him out myself.

"Oh, but who's this?" began number 13 suddenly.

At the same time I started to hear footsteps coming down the corridor, gradually growing louder as the person came closer and closer. I froze, not sure what to do.

"Oh, my…What a mind…Such brain power! So many brain waves to be eaten…so tasty…" hissed number 13, as the owner of the footsteps came into view.

It was the man in the trench coat from before on the street. He was still in his trench coat, but he was also wearing a brown pinstripe suit and converse with it. He was tall and thin, with such messy hair it was like he just got out of bed. He had an air of confidence about him, caused by the way he held his head straight like he was ready for anything that the world threw at him.

As I watched him walk up, I got the feeling I had from before, a feeling that I couldn't quite decipher. All I could get out of it was that this man was not what he appeared to be.

"Oh, I bet you would do anything to sink your fangs into my head, you Cerebrivore you. But that isn't going happen. Plus, I don't think you could handle all the brain waves my mind can dish out," said the man in a British accent, stopping right in front of me, facing the pipes and not noticing me through the dark. "Now where are you hiding?"

My eyes widened. This man sounded like he knew all about number 13. He even knew the name of its species. It was now obvious that what I could get out my feeling was true. This guy was not a normal person. Could it be possible that he was another Alien Hunter? wondered my brain. One that I didn't know about? Was he another being from Alpar Nok?

"Oh…you smell so much more appetizing than the boy…Oh, my! I haven't seen so many goodies in one person on this planet in all my travels," said number 13.

You can practically hear the desire in snake-y voice. If it wasn't drooling before, it had to be now. What powers did this man have in order to have so many brain waves? How smart was he? Those questions and more swam in my mind. I was unable to really think of anything else at the moment.

"Boy?" asked the man, looking around.

Did I mention it was very dim in the corridor? My flash light had failed a while back and I wouldn't be surprised if the guy couldn't see me. I only knew he was there because of the sound of his footsteps and the fact that I could barely see him in the dim lighting situation. But even though I could hardly see him, I was sure the he was the man from before. After all that feeling I had did come back, didn't it?

Just then the man reached in his pocket and took out a flashlight, clicking it on with a flick of his thumb. He shone the beam of light around the corridor until it landed on me, still standing there.

"Oh. 'ello. What are you doing here?" questioned the man, a quirky smile appearing on his face.

I opened my mouth to answer, but number 13 spoke for me. "He was trying to kill me. Weren't you, Daniel?"

"Trying to kill a Cerebrivore? How…? Wait, you're name's Daniel. Do you have a last name?" quizzed the man.

"Uh…Not really …," I muttered. For some reason I didn't want to lie to the guy. After all he could be one of my kind. But there was also something else about the dude that made me want to trust him, that made me want to tell him the truth.

"Daniel X?" the man asked carefully, his eyes boring into me.

I hesitated for a second, my paranoia kicking in. What was this guy getting at? What did he know? But then I shook it all out of my mind. If this guy was from Alpar Nok, it would make sense that he would know a thing or two about me right? So what should I worry about? Plus, this guy seemed trustworthy. So I nodded yes to the man's question.

"Oh, Daniel X! I'm so glad that I get to finally meet yah. Nice job with that Vermgypian, by the way. Nasty fella. Kidnapping, drugs, murder, ect. I've been after him for quite some time. But he got away…and I was kind of busy with other things…I would've stopped him in the nick of time if it came down to it. I'm good at saving things in the nick of time…And Judoon would've stopped him sooner or later, but by the time they would've done that, it would've been too late for Earth. They're a bit slow on the up take…Oh, I'm so sorry about what happened with your home planet. I really liked Alpar Nok. Nice beaches. I would've helped…but well…it's complicated," babbled the man, holding out his hand for me to shake. "I'm the Doctor, by the way."

The Doctor…My eyes widen and despite myself, my heart began to speed up. So that's who he was. That's was why I was getting a strange feeling about him. I have seen that name surpass The Prayer on The List quite a few times, but always for a short period of time, like an hour at the most. And this always seemed to a line with weird happenings in London. Like during those Christmases: the one with the space ship over London, the other one with the Christmas star, and the latest one with the Titanic. And then there was that time with the ghosts. I was in the Amazon Rainforest when it happened (tracking down number 32), so I didn't see the ghosts personally, but I did see the Doctor's name on the list for a short amount of time. There was also that one weird time when the Doctor's name surpassed someone else that surpassed The Prayer. The Master was its name, and it was on there for months, until the Doctor surpassed and then suddenly they were both off The List.

I now knew that this man was not from Alpar Nok. He was someone, something else. Something that was, at least at times, more dangerous than The Prayer. And he was standing right in front of me, a goofy smile on his face. I didn't take his hand.

"Oh, sorry. Didn't mean to startle yah. Yes, I know about you and your little alien hunting thing, but don't worry. I learned about you from this UNIT file I happened to look at one time. UNIT and Torchwood have loads on yah. They don't mind you doing whatever you're doing, just as long as you keep out of trouble you know. You actually help them. Not sure why UNIT hasn't tried to make you one of their agents yet though…probably because you're too young. But that doesn't really matter, does it? You've taken down plenty of aliens…but I think they have the 18 age minimum thing like all government agencies. But they're not really government are they? And it's not like age hasn't stopped them before…" rapidly babbled the Doctor, putting his hands in his pockets.

All I could do was stare as the Doctor continued to talk, questions starting to fill my head like a waterfall filling a pool. What was UNIT and Torchwood? How did they find out about me? But most importantly, who was the Doctor? He had surpassed The Prayer plenty of times on The List. It was obvious that he was dangerous. But here he was, gibbering way a motor boat, with that silly cartoon smile of his. If he was dangerous, he was surely hiding it very well. I was not underestimating him though. I had learned that underestimating people, especially people that are known to be dangerous, isn't the best thing I can do.

"So many tasty brain waves…Must. Eat!" suddenly hissed number 13.

Its words shut up the Doctor instantly, but just as that happened, snake-y somehow gnawed through his pipe and lunged at the man. Using my quick reflexes, I managed to push the Doctor out of the way, number 13 missing his head by mere inches. Not allowing myself to think about how I just saved the only being that was dangerous than The Prayer, I speedily took out the ultra-violet light stick out of my backpack and shone it at number 13 who was gearing up for another attack at the Doctor.

Number 13 started to sizzle under the light as it began to back away. I followed it. If I could keep it under the ultra-violet light long enough, snake-y will turn into nothing but a pile of ash.

"Didn't anyone tell you that gluttony is one of the seven deadly sins?" I taunted, pressing the ultra-violet light stick closer.

Snake-y hissed and backed up some more, but now it looked like was getting ready to jump back into the hole in the pipe it had just made. If it got back into the pipes there was no way I was going to get it in time to save its next target. I had to get it here and now. I was gearing up to try and catch it in mid-jump, when suddenly the Doctor took his ultra-violet light stick (from his pocket?) and pressed it towards number 13. Together we managed to back snake-y up against the wall long enough for it to turn into ash. Number 13 was terminated.

A silence came between the Doctor and me with the only sounds being the slight hum of the ultra-violet light sticks, the far away drip of water, and the sound of us breathing. I really didn't know what to do next. I had the-sometimes-number-1-on-The-List right next to me, and I didn't know whether I should thank him or kill him. Meanwhile the Doctor just stood there, staring at the pile of ash with his motor mouth closed into a grim expression.

Right then and there I saw the darkness in the man's eyes, the darkness that was probably what made him even more dangerous than The Prayer. But the darkness was also accompanied with such a deep sorrow that I knew I could never understand it. But beyond his eyes in the blue-ish ultra-violet light, he looked softer, and possibly gentle and kind.

"Well…now that that's over with…," began the Doctor, putting the ultra-violet light stick back into his pocket.

He didn't finish his sentence though for instead he went over and picked up his flashlight from where he dropped it, his face taking on the harsh light it cast and making him seem like he was hundreds of years old and half dead.

"Uh…wanna get some tea?" asked the Doctor in light tone that I knew was masking something much darker.

I didn't know what to think of the guy. He seemed crazy, caring, and hazardous all at once. It was strange and I again asked myself the question as to who this Doctor really was.

"Who are you?" I quizzed, finding that I couldn't help myself from asking that question out loud.

"I'm the Doctor. Last of my kind. 906 years old. Stuff of legends. Time traveling alien…now…you want to get some tea or not?" answered the strange man in the trench coat.