Clara opened the TARDIS door slowly. 'Careful' was the word of the day. Subtle. The Doctor was observant, intuitive and startled easily. He would know something was up just by looking at her face. But right now he sat with his back to her, engrossed in some task. The perfect time to approach him.

"Hello!" she called.

He started up at the sound of her voice, hand knocking a micro soldering iron to the floor.

"You're cheerful this morning," he said, bending to retrieve the tool. "And you're usually in a terrible mood when you have to work. School holiday?"

"School trip," she explained. "Fresh air. Sunshine. No classroom. Why shouldn't I be cheerful?"

"I'm feeling suspicious, Clara," he said, shifting his attention back to the array of parts spread out before him on the work bench. "Why am I feeling suspicious?"

"No idea," she said. "So, what have you got on today? And don't say repairs, you're always doing repairs."

"Repairs," he said. "Then I'm popping over to Kentaurus. I have an overdue library book."

"An overdue…sorry, did you say library book?"

"Yes, and the librarian is a stickler, in every sense of the word." He picked up and discarded several tools before settling on a needle file. "The inhabitants of Kentaurus are a distant branch of the Erinaceidae family of Earth."

Clara shook her head. "English teacher, remember? No big Latin words unless they relate to literature."

"Giant hedgehogs," the Doctor explained. "Not terribly intimidating even given their enormous size. But the fines they impose for overdue books, that's another matter." He twisted in his seat and motioned toward the console. "Hand me that thermal paste, will you?"

"Okay, I'll bite," she said, curiosity getting the better of her. "What kind of fines do hedgehogs impose?"

"Hard labor," he said, plucking the proffered tube from her fingers. "And that's when they're feeling generous. But they're burrowing insectivores so their idea of hard labor isn't physically demanding. They usually send me out to dig for worms."

"Ugh." Clara wrinkled her nose. "But why would a time traveler ever have overdue fines? You can just pop back before the book is due."

"The head librarian is an old friend. I browse the stacks, dig a few worms and then we have a discussion of theoretical astrophysics over tea." He smiled. "Well, theoretical to her."

"Can the library wait?" she asked. "I had something else in mind today."

His smile faded, one eyebrow quirking as he waited for her to elaborate.

"This school trip I mentioned," she said in a rush, before she lost her nerve. "We're taking the kids to a small children's zoo in Battersea Park."

"Well, that sounds lovely," he said. "Have a wonderful time."

"No, you don't understand," Clara said, trying not to pluck at his sleeve out of desperation. "The students have been looking forward to the trip for months but one of the chaperones called out ill this morning."

"Give her my regards," he said, snapping on a pair of safety glasses and turning back to his work. "It's nothing to do with me."

"Doctor, please," she said. "I don't ask you for favors that often, do I?"

"A children's zoo," he scoffed. I'd rather dig for worms with my teeth."

"All you have to do is tag along with me and keep the little terrors from running headlong into the monkey pit," she said. "Shouldn't be too difficult. Your eyebrows alone should be enough to keep them in line."

He grunted noncommittally. Clara could sense him weakening.

"They've been looking forward to this for months, Doctor. And so have I." She was but she wasn't above using guilt to get her way. "You wouldn't want us to cancel the trip, would you?" She widened her eyes. That always did the trick. "Not when you could help."

"They're not going to cancel because you're short one chaperone."

She stared at him for a long moment. He held her gaze unwaveringly.

"Fine," she said, throwing up her hands in defeat. "You win. No, they won't cancel the trip but I really, really want you there, please. They've paired me with Mrs. Watson and she's so boring. I'll lose my mind if I have to listen to her push her latest multilevel marketing scheme at me. I think it's Herbalife this month."

He straightened and dragged the plastic apron over his head. He said nothing as he folded it neatly and set it aside on the bench. He shrugged into his coat.

"Herbalife, eh?" he said, doing up the buttons slowly. "I wouldn't wish that on anyone."

Clara blew out a breath, shoulders loosening as relief flooded through her.

"So you're coming?"

"Yes," he said. "You owe me one, though."

"Anything. I'll even help you dig worms and pour the tea," she said. "Cross my heart. Now come on, we leave in thirty minutes and you need to change."

He glanced down at his usual clothing, crisp white shirt, waistcoat, Crombie. "I don't need to change," he said. "This is perfectly acceptable attire for a zoo trip."

"Yes, if you're going to do magic tricks and make balloon sculptures," Clara said. "Something a little less conspicuous. And hurry up."

Clara nudged the Doctor as they approached the children's play area. He stomped along with hands shoved in the pockets of his hooded jacket, head lowered. She met his scowl with a sunny smile.

"Admit it," she said. "You enjoyed yourself today."

"That agouti was absolutely wrong," he said.

Clara sighed. "I can't believe you're still upset about it."

"I don't care how cute you thought he was with his furry little face and beady eyes," he said, imitating a credible set of whiskers with wiggling fingers. "He employed a clear ad hominem attack and false attribution." The Doctor kicked at a stone on the path, watching it bounce to the side.

"I'm not listening to you complain about logical fallacies," she said. "You were arguing with a rodent. Which I suppose for you is a good time."

He muttered something inaudible under his breath. Clara grinned and nudged his shoulder as the cheerful noise of a calliope carried to them through the air and the sight of tiny twinkling lights came into view.

"There's the carousel," Clara said, bouncing slightly on her feet as she looped her arm through his and pulled him forward. "Come on, I want to take a turn before we leave."

"You go ahead," the Doctor said, dragging his feet and trying to extricate his arm. "I'll take the next turn, after I've reviewed the current safety inspections and had a look at the motor."

Clara poked him gently between the shoulders as they waited in the queue. "You're going to have fun whether you like it or not," she said, ignoring his baleful look as they stepped up to the platform together.

"This one's mine," she yelled back to him, not sure if he could hear her over the shouting and calling of the excited students. She mounted a white horse adorned with a garland of carved and painted roses and wrapped her hands around the pole.

As the carousel started spinning, Clara laughed at the giddy, swooping sensation in her stomach. The ride picked up momentum and she shook her head, feeling her hair lift in the breeze. She'd forgotten how much she enjoyed simple pleasures like silly park rides and spending the day with her best friend. Her horse rose and fell and everything around her was a blur of light and color and then she heard a drawn-out guttural noise

She opened her eyes, joy forgotten and teacher's intuition on high alert. Too much pop and ice cream combined with the motion of the carousel, she should have expected it, but everywhere she looked she saw only happy shrieking children. She couldn't find the Doctor at all. Had he slipped off the carousel when she'd been distracted?

She scanned the crowd as the ride made a few revolutions. He'd be easy to pick out in his all-black ensemble, but she saw nothing as they whipped by.

She heard the moan again, rising above the shrill sound of the calliope. Clara dismounted slowly and moved cautiously around the platform, using both hands to keep her balance as she walked between jumpers and standers. She scanned each face as she passed, looking for any tell-tale signs of distress but received only curious looks in return.

Her heart leaped in her chest when she finally found the source of the pitiful sounds. The Doctor sat slumped in the corner of a stationary chariot, head in his hands. She slid into the seat next to him and patted him on one knee.

"Clara," he said, voice hoarse and rather desperate sounding. "Everything is too bright. And noisy. And much too spinny." He opened his eyes and then squeezed them shut again. "Is there an off button for this thing?"

He looked terrible, his face grey and drawn, a sheen of sweat glistening on his forehead. It could only mean one thing and it was a very bad thing, especially in a crowd of impressionable children.

"It's starting to slow down," she said. "Hang on."

And don't be sick, she begged him silently. Hold it together for a few more minutes or we'll have a jolly round of sympathy spewing and a school trip they'll never forget.

It seemed to take forever but finally the ride stopped. Clara helped the Doctor to his feet, looping his arm over her shoulders and gripping him around the waist. He wavered and it took all of her strength to keep him upright.

"One foot in front of the other," she told him. "Just concentrate on moving your feet and we'll get you off here as quick as we can."

As they neared the edge of the platform, Clara felt a hand tugging at her sleeve and she twitched it off, focused on guiding the wobbling Doctor through the milling throng of riders.

"Where are you taking him, Miss?"

Before Clara could answer, a second child chimed in.

"Why has he gone that funny color?"

"Is he going to be sick, Miss?" said the first student, excited at the prospect. Little beast.

The children within earshot started to giggle, pretending to fall about as they clutched at their stomachs, making exaggerated retching noises.

"Stop that at once," she snapped. "Mr. Smith isn't feeling well. Now make yourselves useful and find Mrs. Watson. Tell her I'll be right back."

She braced herself on the railing, trying to take most of the Doctor's weight against her.

"One big step down," she said, ignoring the children with their eager, expectant faces. He missed the edge completely and took three crashing and stumbling steps forward. She hauled him back by one arm.

"Everything is still moving," he moaned. "Did you put me on another carousel by mistake?"

"No, of course not," she reassured him, guiding him away from the ride with a hand on his back. "C'mon, this way. You're heading for the aviaries."

As he staggered in the other direction, he stopped suddenly, gave a strangled cough and clapped one hand over his mouth.

"Not yet," Clara warned.

She knocked the top off a nearby bin, took a quick glance inside for anything noxious and helped him lean over. He gripped the edge of the can, liner bunched in his hands, breath ragged.

"Slow breaths, okay?" she said. "And think about pleasant things."

"So I shouldn't think about this half-consumed candy floss right under my nose," he said, propping an elbow on the rim and resting his forehead against his arm.

"Definitely not."

He sounded better, voice a little stronger, but she moved to his other side, trying to block him from the kids who were craning their necks for a better view. She rested a hand against the back of his neck as he took in deep gulps of air.

"You sure you're gonna be okay?" Clara asked. She'd make all the proper sympathetic noises if he needed to be sick but she'd prefer to avoid it if possible.

He inclined his head as if considering it and then nodded and looked up at her, blinking against the light.

"Still feeling a little dizzy," he said, swiping a trembling hand across his forehead.

"Let's sit you down, then," she said, leading him to a bench under a spreading alder. He fell rather than sat and remained as he landed, legs sprawled and head bowed.

"You're getting some color back in your face," Clara said, trying to fill the tense silence. When he didn't reply, she took one of his hands in hers, trying to ignore how damp it felt.

"I'm sorry, Doctor," she said. "I'm really so sorry. I shouldn't have asked you to come today. You could be having a nice cup of tea with your librarian friend right now instead of nearly losing your lunch in a trash bin."

His hand tightened around hers convulsively and he made a noise low in his throat.

"Okay, changing the subject," she said. "There's a little shop across the way. Can I get you a bottle of water? " She caught her lower lip between her teeth, wondering what would appeal to a slightly nauseous Time Lord. "Or an ice lolly, maybe? My mum would always bring me ice lollies when I was feeling ill."

She made a move as if to stand and he gently pulled her back.

"Come on," she said, tugging against him. "I'll get you something to drink and then we'll have to head back to the coach." She shaded her eyes with one hand, frowning as she watched the other teachers gathering the kids near the gate. "Looks like they're already loading up."

He looked over his shoulder to see where she was pointing and then dropped his head, a hard shudder running through him before he spoke.

"Clara?"

"Hmm?" She mentally counted off the students as they lined up.

"I can't get back on that coach."

She turned back, her attention now focused completely on the Doctor. His face was still tinged green, with beads of sweat standing out on his upper lip and a smear of grime along one cheek where he'd rested his head on the bin. He looked ashamed but determined.

"Doctor, you're a time traveler," she said, trying not to sound as exasperated as she felt. "You've never had motion sickness in your life and now you're telling me you can't handle a thirty-minute coach ride? You'll be back in your comfy chair on the TARDIS before you know it."

He flushed slightly. "It's cramped in there," he said. "And hot. And bumpy." He dropped his voice. "And some of the children don't smell very nice."

She nodded. All this was true. "But we're chaperones," she said, "We have to accompany the students back to the school."

"I can't," he said. "You go on, make up some excuse for me. I'll find my own way back." He tried for a brave smile that faltered quickly. "I'm a big boy, Clara. I can handle it. Off you pop."

Clara frowned, taking a few steps away before looking back to him.

"You're sure you'll be all right?"

He opened his mouth to reply, then shut it again, rubbing a hand across his forehead.

"What would you like me to say?" he asked.

Some raw, vulnerable quality in his voice made her hesitate. Clara caught the eye of one of the other teachers who was making expansive motioning gestures toward the gate and held up one finger.

"I want you to be honest with me," she said, sitting down next to him. "I always want you to be honest."

"Then, no," he said. "I'm not sure I'll be all right." He worried a loose thread on the cuff of his jacket, one knee bouncing in a twitchy rhythm. "I still feel sick and I really don't want to be alone in a strange zoo with an argumentative agouti."

Clara stilled his fingers with hers.

"I'll stay with you," she said. "Zoo doesn't close for a few hours. You can have a quick kip on the bench and we'll figure out a way to get back home after that."

"And it won't involve spinning things?"

"Or horses," Clara agreed. "Or smelly, overexcited children. It limits our options but we'll think of something, okay?"

She patted her lap and he turned and grasped the back of the bench, lowering himself slowly until he was stretched out flat along the slatted surface, head resting against her legs.

"No carousels," he murmured, eyes fluttering closed. "And a grape ice lolly."

She smiled down at him. "Whatever you say."