Disclaimer: I, sadly, own nothing.
Sorry for chapter inconsistency!
The Doctor, Martha, and Jack stepped off of the train. "Remember, you don't know anyone!" hissed The Doctor. Martha and Jack nodded, looking around. Jack started to ask a question. "But where is-" "FIRS' YEARS OVER HERE! FIRST YEARS OVER HERE!" Hagrid saw them and smiled. "'Ello, Harry! Ye alrigh'? Come on, everyone get in a boat!" The three quickly got into a boat together, and Hagrid sent them all off across the lake. The Doctor saw a merman, and the two had a quick chat in Aquan. Then he looked up to see Jack and Martha staring at him with wide eyes. "What?"
Suddenly he gasped. Martha and Jack turned, and there was Hogwarts. A castle, beautiful, with turrets and candles… "We-we're really at Hogwarts." whispered Martha. "Yep!" The Doctor was grinning, and Jack was openmouthedly gaping. The boats gently glided to a stop, and Hagrid led them inside. A stern looking lady was there. "I am Professor McGonagall. You will wait here momentarily, and then you will be Sorted into one of four Houses." She then turned sharply and left. People around them were whispering nervously about what Sorting would entail, as Martha, Jack, and The Doctor nodded to each other. "Remember, ask to be in Gryffindor!" whispered Martha with a grin. Jack laughed, and just then Professor McGonagall returned. "Come with me into the Great Hall." she said sternly, and the first years all huddled together and followed her. They gasped as one when entering the Great Hall. "It's-amazing," said Martha in an awed voice. They were told to sit and wait. Then, Professor McGonagall suddenly reappeared with an old hat. "It looks even rattier than I imagined," whispered Jack. The Doctor frowned and kicked him discreetly. The hat sang it's song (Which Martha, diehard fan, knew by heart), and then the names were called. The three vaguely payed attention until "Granger, Hermione!" was called. Jack and The Doctor looked intently at Martha as she hesitantly went up to the stool and put on the hat. The hat paused, and The Doctor could tell it was having a discussion with Martha in her head.
MARTHA
She put on the hat, which smelled vaguely damp. "Aha," said a voice in her head, "Now what have we here? You aren't Hermione Granger… In fact, you aren't even from this reality!" Martha nervously thought, yes. "I can see what you know you must do. But really, this character? Went with The Doctor when you hardly knew him… I would say you were born a GRYFFINDOR!"
Then it yelled, "GRYFFINDOR!" and everyone clapped and cheered. Jack and The Doctor let out small, relieved sighs. The list went on until "Potter, Harry!" was called, and everyone started whispering. "Did she say Harry Potter?" was the most common. Jack walked up to the stool and put on the hat.
JACK
"…You're immortal." Was the first thing the voice in Jack's head said. He smiled sheepishly. Not my fault, he thought. "I can see that." said the hat thoughtfully. "I can see several things about you, in fact." I can show you more than that, Jack thought suggestively. He could feel the presence in his mind become repulsed. "GRYFFINDOR!" It cried hastily.
"GRYFFINDOR!" As the hall erupted into cheers and shouts of "We got Potter!" The Doctor couldn't help but think that the hat seemed slightly disgruntled as the next name was called and Jack sauntered over to the Gryffindor table. He was so busy musing he almost missed Draco's name, and subsequent sorting into Slytherin, but then suddenly he heard, "Weasley, Ron!"
THE DOCTOR
"How are you friends with that guy?!" the voice in his mind demanded as soon as it was on his head. Did Jack really…? Sorry, so sorry about that, thought The Doctor with a sigh. "Wait, you thought my singing was like a what?" A Zirrclonifian, thought The Doctor brightly. It's a compliment. "I can see," commented the hat, "And my, my, what else is in here? Dear Doctor, you are perhaps the bravest, most loyal, smartest, and cleverest man I have ever seen. You would do well in Ravenclaw, but-oh my? What have we here?" Do not go near that part of my mind. thought The Doctor with a cold fury. The hat sighed. "Oh, dear Doctor. I'm sorry, I'm so sorry. But you know as well as I that that war had to happen, and it had to end." I just wish there was another way… The Doctor thought sadly. The presence in his mind seemed to approve. "Just for that, I can see you are the truest of true. Godric himself would be amazed. You, dear Doctor, are a GRYFFINDOR!"
Jack and Martha, sitting together, saw a play of emotions on The Doctor's face, including unmistakable sorrow, then the hat yelled "GRYFFINDOR!" and everyone cheered. The Doctor gave a forced smile, walked over to the Gryffindor table, and promptly collapsed with a sigh between Martha and Jack. Martha looked worried. "Do-Ron, are you sure you're alright?" she asked, concerned. "…Fine. I'm always fine." he said, and sat up as Fred and George came over. "Knew you'd be a Gryffindor!" Said Fred, grinning. As The Doctor perked up and talked animatedly about possible pranks with the twins, Martha and Jack made baffled faces to each other, shrugged, and listened to "Zamboni, Blaise!" becoming a Hufflepuff. Then they turned to The Doctor. "Why did you just discuss illegitimate things with your 'brothers'?" asked Jack. The Doctor smiled fondly. "I remembered my University days… Me and The Master were basically Fred and George, plus more explosions and sonic tricks. He wasn't always bad!" he added when seeing the looks on their faces. "Riight… Anyways, listen! It's Dumbledore!"
Sure enough, Dumbledore was about to make a speech. He then made the speech which the three vaguely remembered, which included the don't-go-in-the-third-corridor part. After which, all three ate and talked about wizard-safe topics. After they went up to the common room "Doctor, the stairs are really moving!" "You travel in a blue box that's bigger on the inside and you're amazed by moving stairs?" "It's Hogwarts, Doctor.". Then they arrived at the Fat Lady's portrait, and The Doctor kicked Martha to prevent her from squealing. (Jack, surprisingly, was doing a good job of acting.) Before the three went to their rooms for the night, The Doctor grabbed them and pulled them together. "Remember, you lot-anwer to your new names, and Jack, no flirting or I think you'll break the book." Jack rolled his eyes and sighed, and Martha giggled. "What's so funny?" "…I think that Ron and Hermione are going to be in switched roles tomorrow…all year, probably." They laughed, and Jack's eyes got huge and he whispered, "Potions!"
Everyone went to their beds still chuckling.