Prompt fill: The Doctor turns into a child and can't remember the fam, thinking she's still a student of the Academy on Gallifrey and asks for her parents, while the fam wait for the effects to wear off.

I've sort of filled the prompt? I've not really had experience interacting with children so I had to adapt it a bit. I meant to get this posted before today's season finale (woah: bombshell!) but didn't manage it (thanks mental health).

"Doctor!" Called Ryan as he cautiously walked down the empty corridor, ignoring his reflections that flanked him at either side. Other than the footsteps of Graham and Yaz, along with his own as they walked on the metallic floor behind him, there was no sound.

"Doc?" Graham got no reply to his yell. "You think she's even down here?"

"They said she was down here," said Yaz. "We've just got to keep going until we find the right room."

They had gotten separated earlier in the day after the Doctor had requested use of some equipment that their hosts, the Estradi, had available. She had been unwilling to tell them what and why she needed it, just told them to find her in exactly 3 hours. That time was now up.

They peered into another room, expecting it to be as lifeless as the other rooms they had inspected. It would seem this wing of the facility was rarely used, especially during the current crisis. But it wasn't empty.

The Doctor stood with her back to them, head bowed, as she ran fingers across the buttons and leavers of a control console, but didn't seem to be actively using them. She didn't show any indication she was aware of their presence.

"Doctor?" Ryan asked.

The Doctor jumped and turned to them, fear on her face.

"I wasn't touching anything, I swear!" Her breath hitched as she stared wide-eyed at the three humans. Her arms pressed protectively against her chest.

"Doctor," Yaz asked, "are you alright?"

The Doctor's brow wrinkled.

"Who's Doctor?"

Yaz paused, shocked.

"You're the Doctor."

The Doctor shook her head, hair flying.

"No. My name is Theta."

The humans stood stunned, uncertain what to do now. Was the Doctor possessed? Replaced by something? But the person standing in front of them didn't seem malevolent, just confused and perhaps a little scared. Somehow she sounded young. Innocent.

Yaz tried to smile and hoped it looked genuine, hiding the butterflies in her stomach.

"How did you get here, Theta?"

The Doctor, Theta, shuffled her feet, hands wringing as her gaze flickered across the three of them.

"I don't know." She said eventually. "I just woke up over there." She pointed at what looked like a dentist's chair surrounded by machines and equipment. Tears sprung up in her eyes and her breathing speed up. "I don't know where I am and I'm not me anymore."

Yaz's heart broke at the sight of her friend in tears.

"Hey, you're ok. You're safe, we won't hurt you. Why don't you tell me about yourself and anything you remember before you woke up here and we'll work out how to fix what is wrong?"

Theta shook her head, getting more distraught.

"I don't know who you are. I'm not supposed to talk to anyone I don't know. I don't know what's going on."

"Yaz," hissed Graham. "What is exactly going on? What's wrong with the Doc?"

She looked over her shoulder at him and shrugged. Her attention then switched back to the Doctor.

"What about after you woke up here? Surely you can tell me that, hey?" The Doctor nodded. "You said you woke up on that bed. Was there anybody with you? Has anything changed since then? Any lights on any of the equipment that have turned off or on that you remember?"

"No," Theta whined. "Nothing." Her body seemed to collapse on itself and she fell back onto the console behind her, hands covering her face. Quiet sobs wracked her frame.

"You're really scared, aren't you love. Would you mind if I gave you a hug?"

When Theta didn't respond Yaz cautiously stepped forward and slid an arm around her shoulder, ready to pull away at the first sign of negative reaction. Theta didn't move at first but then suddenly latched onto Yaz, fisting her hand in her shirt and pulling her closer. Yaz just held onto her and stroked her hair as the Time Lord, or whoever was inhabiting her body, sobbed into her shoulder.

Graham and Ryan, unable to do anything than idly stand by, started to investigate the rest of the room.

There was the chair that Theta had pointed at in the middle of the room, the bank of controls of which the Doctor, or Theta or whoever it was, leant against one end that ran across most of one side of the room and a large screen above it that filled the rest of the wall. The rest of the room was empty. It had no windows and only the single door they had entered through.

Ryan poked at some of the wires that covered the 'dentists' chair. They were similar to medical leads with small sticky pads at one end but they were tangled and scattered, as if someone had taken them off in a hurry. They were connected to the equipment that surrounded the chair at either side. Graham raised his eyebrows at Ryan over said equipment, thoroughly lost and unable to understand any of the displays and lights that peppered the machines.

It seemed to take a while but Theta eventually sobbed herself out. Yaz rubbed her back as she withdrew from the embrace and wiped her eyes with her sleeve.

As Theta composed herself again Yaz stepped back to give her some space and looked over to see the boys crossing the room back to her.

"I don't understand any of that stuff," said Graham

"If only we had the Doctor, she'd understand everything," Ryan snorted. "There's irony for ya."

"Emm," interrupted Theta, sniffing heavily. "There is one thing." She stuck a hand in her pocket and withdrew something. "When I woke up I had this in my hand."

She held out the psychic paper, its surface covered in the same swirls and circles that were dotted through the Tardis.

Yaz reached for it but Theta pulled it away. She held the psychic paper against her chest and looked at them suspiciously.

"I need to know your names."

"Did we not say?" questioned Graham, more amiable towards Theta now he didn't consider her to be a threat. Surely someone that broke down into floods of tears couldn't mean anyone harm? She truly seemed scared. "Sorry, that's very bad manners. I'm Graham."

"An' I'm Ryan."

"Yaz."

Theta shoulders sunk as her eyes were glued to the psychic paper. She nodded to herself, seemingly coming to a decision. She looked up at them.

"It says I should trust you. And only you." She waved the paper in their direction. "Did you write this?"

"No," replied Yaz, "but I know who did. She's a friend of ours and I would trust her with my life so I know you can too."

Theta nodded to herself again.

"It says I should show you this."

She crossed to the middle of the bank of controls and after examining the psychic paper she pressed a few buttons.

The big screen flickered on. The Doctor's face appeared.

"Fam!" she exclaimed. "Sorry for running off on you earlier I had something important to do. I promised you answers and now is the time to give them."

Out of the corner of his eye Ryan saw Theta suddenly start and pull her hair in front of her eyes, then running a finger down her nose, examining the picture on the screen with the bits of body she could see and feel.

"That's this body," he heard her murmur.

"I know how to help the Estradi," continued the Doctor. "The only problem is that I can't actually remember it, but I know I learnt it as a child. That's the problem with being several thousand years old, the things I learnt in the Academy have been long forgotten.

"The Estradi have the technology to help me remember but there are side effects. I can't find it in any other way, it's not in the Tardis databanks and the information was never passed outside my home planet. Going home is… well, it's not an option. The only place it is is in my head. And I. Just. Can't. Remember." She looked off to the side and smacked the side of her head with a fist. "Stupid brains. Why can't I just remember?" She seemed to suddenly remember that she was on camera and refocused on the screen.

"And before you ask the Tardis telepathic circuits are no help, it's the wrong type of information. I won't go into detail why but it's like putting petrol in a diesel car. It just won't work. Unfortunately for me.

"I'll probably regress, that's the main side effect. Actually if you are seeing this I guess I have. Physically I'll still be me but mentally I'll be the age I was when I learnt what I'm looking for. A child. Please be gentle with me, I'll be young and I'll be scared.

"I've reconfigured the Tardis translation circuit so hopefully you'll understand me. If you can't then the modification has failed, which wouldn't be surprising as the circuits weren't meant to work in that direction. Try your best." Her face suddenly went serious.

"There is one important thing - don't ask me about myself. I know I haven't been forthcoming about my past and I trust you not to pry. I have my reasons not to share. In that vein don't let me talk about myself. I shouldn't as I was taught not to share information with outsiders but I thought I'd say just in case."

She paused for a second to retrieve something from inside her coat.

"In my pocket there should be this." She held up a small elongated cube, about the size and shape of a USB memory stick, black with a stripe of blue light down one side. "This is a data recorder. Whatever you do do not let me lose it or what I am about to do will be pointless." The recorder was tucked back in her pocket again. She sighed, eyes boring straight through the screen.

"This'll wear off, I promise. I don't know how long it'll take but it will. Please just get me into the Tardis and keep me safe. Don't be scared, I'll be back to normal soon."

She swallowed heavily and gave a little nod.

"See you guys on the other side."

She gave a grin, slightly nervous around the edges and the screen turned blank.

There was silence that followed the Doctor's message, each person present taking the time to gather their thoughts.

Both Graham and Ryan were internally panicking, neither had experience with children and didn't know what to say to their friend-turned-child even if she was still in her adult body. And the Doctor had said that she was the socially awkward one!
On the other hand Yaz's nerves had settled as she could stop worrying about her friend. She just had to believe that the Doctor and her usual odd personality would return to them in time. Meanwhile the three of them had a child to look after. The Doctor had confirmed what Yaz had suspected - behind the Doctor's adult face was a child - her as a child.

Theta was the first to move, digging in her pocket with one hand. Yaz was next to shake off the stillness that had settled, quickly followed by Ryan then Graham as they remembered that they weren't the only ones in the room. They turned to Theta to gauge her reaction to the Doctor's revelations.

Theta was staring at something lying in the palm of her hand. It was small, black and rectangular with a blue stripe of light, just like what the Doctor had shown them on the video.

"It was in my pocket," she said quietly, almost in wonder. She suddenly looked up, realising she had an audience, fingers clamping over the data recorder. "I'll keep it safe. Promise." Her voice was still quiet, husky with a little waiver. Yaz thought she might cry again but she straightened herself up and stuck out her chin.

"So I'm in her? Swapped bodies?" She tentatively asked.

"Erm, yeah," nodded Yaz, unsure what else to say.

"Does that mean you can fix me?"

"Sure. We've just got to wait and it'll sort itself out on it's own." Because you could hardly tell a child that they weren't going to exist any more at any moment in the (hopefully) near future. If Theta was still under the illusion that she had swapped bodies with the Doctor Yaz was not going to shatter it. She turned and gave hard stares at the others to ensure they didn't contradict her.

Theta seemed convinced and pocketed the recorder. She paused, one hand frozen halfway out of her pocket.

"I still don't really know who you are. What species are you?"

"Human," said Yaz

"From Earth," pointed out Graham, remembering the humans they had met that had lived entire lifetimes without setting foot on their planet of origin.

Theta's eyes widened in wonder.

"I've always wanted to meet a human. My teacher thinks you are animals barely evolved down from the trees. But I've found your history fascinating! Like the-" she stopped, lips almost comically pressed together, one hand pressed over them as if to stop the words from tumbling out. The hand was cautiously removed.

"What time are you from? I'm not allowed to say anything that is in your future." She looked to the side, shoulders sagging. "I don't want to get punished again." She added quietly.

"The 21st century. But we're time travellers so we've been to the future. Don't worry, we won't tell if you say more than you should if you won't."

"The 21st century," she murmured to herself. "If that before or after the-'' she cut herself off. "I've done it again." She sounded miserable. "This mouth won't stop talking sometimes. Stupid Theta, stupid."

Hey," said Yaz. "Knock it off, you're not stupid." Theta looked abashed. Yaz held out a hand to her. "Come on, We'll take you back to the Tardis."

"You have a Tardis?!" She bounced to Yaz's side, bright-eyed once more. "I've studied the dimensional engineering of Tardis's but I've never been in one. One day I'm going to have a Tardis and explore the universe. First stop Earth!"

Yaz couldn't help but grin at Theta's enthusiasm. And feel a little pride that the Doctor really had achieved her childhood dream. Not that she could tell Theta that. But she could tell the Doctor when she was herself again.