Fantastic (Harry potter/doctor who crossover)

The chamber within the chamber

Donna's POV

I watched as the Doctor slammed the door. If he'd done that to me I'd open the door again and slap him in the face.

"So what exactly is it that the ghost saw?" I said to him. He ran towards the closet and rushed into the TARDIS. I followed him so that maybe he'd answer me. 

"Doctor!" I shouted. "Is it a Boggart or is it somethin' else?" 

"I can think of maybe 4 possibilities," he said. "Wait...6....no...3. I hate probabilities."  He smacked his head. "THINK you old brain!"

"What would look like a basilisk to scare a ghost?" I said. 

"Something scared. Something taking in everything around it and using it to it's advantage. Something that wasn't supposed to end up in the..." he trailed off. "Come on!" he shouted and ran out the TARDIS again. 

Yay. More running.

We sprinted down the steps leading to the entrance hall, (getting a lot of strange looks from students passing by) ran through the great oak doors, and ran all the way down to the lake. 

"Okay..." I panted when we stopped. "Why're we here?" 

Instead of answering me he pulled out his sonic screwdriver. He pointed it at the lake and roved around the same area. "Oh come on you useless thing...work!"

"Why's it not workin'?" I ask.

"The atmosphere. You know that technology doesn't work at Hogwarts." he said.

"Oh yes. How could I forget that your alien technology wouldn't work in a magical castle!" I snapped. "If you're gonna mix up worlds why not make em incompatible!"

"Oh honestly did you expect space technology to work in the magical world?" he said as he continued to wave his screwdriver around the lake.

"It would have been nice!" I said.

He suddenly jumped and started running again. I, again, ran after him.

We ran till we had gotten to what was the edge of the lake where it met the hill that the castle rested on. I then noticed that there was a ginormous whole in the ground, making what looked like a giant tunnel. 

"Come on." he said as he hopped through the hole. 

"Oh you've gotta be kiddin' me." I said. But I knew he wasn't so I pursued. 

We went on for ages with the help of the light coming from the screwdriver, until we walked into the cavernous chamber, and my jaw dropped.

It was just like the books. Huge, lit with a subtle green hue, and in the middle stood the gigantic statue of Slytherin. At the foot of the statue I saw the giant snake skeleton, and what looked like a crashed space ship. 

I didn't get a really good look at it before the Doctor pulled me aside behind a wall of rock. I started hearing a conversation coming from the space ship.

"...and then we'll see if we can inhabit it while we find a way to get out of here!" said a scratchy and rough voice.

"So...we're on a fictional dimension? I didn't even realize this was a universe." said a second raspy voice. 

"Oh well maybe because you don't read, you dingus!" said the first voice. 

"When's Frank gonna be back?" said the second voice.

"When he's finished scoping out the place, Phil!" shouted the first voice. "Now hand me that energy conserver." said what I could guess was the leader of Phil and Frank. 

"When do you think the ship is gonna be fixed Dan?" asked Phil. 

"Well, now phil I'm not sure. This ship wouldn't even need fixing if you freaking knew how to fly it! I shouldn't have trusted you with the control panel. The gravity magnet will take ages to get back into it's holding station." said Dan. 

"I like pushing buttons." said Phil. 

There was a thump and another raspy voice swearing from the other end of the chamber. 

"Franks back!" Dan and Phil shouted at the same time. The doctor and I looked over the corner. I almost laughed and screamed at the same time. 

From the conversation I heard I was not expecting these things to look like gelatinous serpents with sharp teeth and...yellow eyes. *

"Frank! What's it like up there?" said Dan.

"Weird! I tried to scare a little pale girl, but I wasn't able to copy anything! I didn't like her so I left." said one of the serpents as he slithered over to the other two. 

"Well what else did you see?" said the other snake who I think was Phil.

"Oh it's an old building. Full of human children and a few older ones. I tried blending in but, hey...do you guys feel that?" he trailed off. Frank's head started turning in our direction.

"Run!" the doctor whispered in my ear, before the snakes could even see us. We tore down the tunnel as quickly and quietly as we could. 

We ran up towards that castle, into the entrance hall and up all the stairs towards the astronomy classroom, not even checking to see if any weird alien snakes had followed us.

"What were those things??" I asked as we slammed the door to the TARDIS.

"They're a species of Multi-forms, they link with other living things psychically to copy another life form." he said quickly. "THAT'S why Myrtle saw the eyes. They connected with her and her last experience with large serpents coming out of the sink. And their ship crash landed because of a little rookie who was too eager with the buttons. Well, I can relate." he added with a laugh. 

"Are they dangerous?" I asked.

"Some of them can be, but the ones down there seem quite slow, so I wouldn't really worry about them," he replied. "But they have an energy conserver, if I can get it from them I could speed up our departure." he said with a twinkle in his eye. 

"Oh, do we have to?" I asked. 

"I told you we can't stay here long," he said with a cross look. "The longer we stay the smaller the hole that we made will get, and this pod is charging too slow, so by the time it recharges, it will be too small to fit through. We have to speed up the process and get out of here, cause if it gets too small and we try to fit through, then we'll only destroy this universe and Harry Potter won't exist anymore." he ended with a sinister look. "So! We have to hurry this up and get the hell out of here. But first we need that energy conserver."

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* this species is the same as what Prisoner Zero was on the show.