"Peri, wake up!"
She mumbled in her sleep, but her eyes remained closed. Sighing, the Doctor climbed onto the bed and tried again. "Peri!" Still nothing. He poked her cheek a few times. Of course something like this would have to happen after she'd been out clubbing with those people she'd met at the lake. He'd have to give her a proper lecture about the effects of alcohol on the human body, but for now he'd settle for getting her up. As much as he hated to admit it, he needed her help.
Finally, he'd managed to wake her by jumping onto her shoulders and bopping her on the head. Even so, she'd only startled a bit before rolling over and sitting up. "Good! You're up."
She rubbed her eyes and gazed blearily at him. "Doctor...?"
"No, that's not the alcohol. As you can see, we've got a small problem on our hands."
"But Doctor..."
"While you were out gallivanting around, I was busy with some routine TARDIS maintenance. I don't know how it happened but somehow the chameleon circuit got crossed with the..."
"Doctor," said Peri, a hint of a smile playing about her lips, "you're a kitty."
"A kitty? A kitty?! I, Perpugilliam Brown, am NOT a 'kitty'! I'm temporarily disguised as a member of the genus felis, or more appropriately felis sylvestris catus."
Peri wobbled a bit where she sat. "So...you're a kitty."
"If you want to get technical about it, I would appear to be a Maine Coon. Suits me well, I think. The breed is known for it's above-average intelligence-"
"You're a chubby kitty." She leaned forward awkwardly and poked him in the stomach.
"It's fur!" he said indignantly. Peri only laughed and fell over on the bed. The Doctor lashed his tail. "The things I have to put up with...go on, get it out of your system!"
After a few minutes, her giggles subsided. "How did this happen?" she asked, gesturing at all of him.
"Well, I was trying to repair the chameleon circuit while you were out and there was a power surge right when I was...you're still drunk, aren't you?" Peri was lying across the bed and had started trying to pet him mid-speech.
She nodded, then said "Kitty!" and started giggling again. "You're purring!"
"I am not," he said, purring as she scratched under his chin. "Now if you've finished playing around, I need you to help me fix this. This circuitry requires something more dexterous than paws and I think under my instruction, you ought to be able to re-wire it in about..." he trailed off as he realised she'd fallen back asleep. "Oh, no. No, get up! You've got a job to do."
The Doctor had put his paws on her shoulder to shake her awake, when suddenly she grabbed him and cuddled him to her, rolling over in the process so she was almost on top of him. "Peri!" he exclaimed. He tried to wiggle free, but she just held on tighter.
He huffed. "On second thought, I think you'd better sleep it off first. I can't have you mucking around with the circuit in this condition. You'd probably turn the TARDIS inside out! So you lay there, and I'm going to wait right here and make sure you're resting properly."
If he didn't know any better, he would've sworn the TARDIS was laughing at him.