The Doctor opened the door and a woman fell on him.
Clara instantly recognised the Welsh songstress. “Is that Shirley Bassey?”
“Probably not,” said the Doctor, lifting the woman up into his arms. “Could you take a look outside, see if there's a double-decker bus there?”
Clara looked through the open door. “Yes,” she said. “On the Moon. There's a double-decker bus on the Moon. With Shirley Bassey in it.” Clara wasn't sure how to take this turn of events. It was a bit odd even by her own recent standards.
She followed the Doctor to the TARDIS medical bay. “Is she sick?”
“Not sure,” he said, depositing not-Shirley on the examination bed and waving a couple of instruments over her. Finally he sighed loudly and said, “There's nothing wrong with her.” He bent down next to her ear. “Iris!”
The woman sat bolt upright. “No need to shout.”
The Doctor rolled his eyes in irritation. “Why did you fall on me if there's nothing wrong with you?”
“A girl has to get her excitement from somewhere.” She looked at Clara. “He's so much more handsome with a few years on him, don't you think?”
“Um,” said Clara, not wanting to commit to anything in that regard.
The Doctor muttered something alien and probably rude. “Iris, this is Clara Oswald. Clara, this, I regret to say, is Iris Wildthyme.”
“He protests too much, doesn't he?” said Iris to Clara. “You should have seen him when he was younger, wandering about pretending that he'd never heard of sex and had been woven on a loom.”
Clara wanted an answer to what she felt was the important question. “If you're not Shirley Bassey why do you look like her?”
Iris shrugged. “I am what I am.”
“She likes to copy other people,” said the Doctor.
Iris gave a mirthless laugh. “Oh, and you never do that, do you?”
Clara caught up. “Is she a Time Lord? Iris, are you a Time Lord?”
“Of a sort,” said Iris vaguely.
Clara turned to the Doctor. “Shouldn't you be a bit... happier about all this?”
“We don't get on,” he said tightly.
“He's madly in love with me,” said Iris. “I turned him down once and he's never forgiven me.”
“She lies a lot,” said the Doctor to Clara.
Iris hopped off the examination table and brushed imaginary dust from her clothes. “Takes one pathological liar to know another,” she sniffed.
“So, you're fine, shouldn't you be on your way?” asked the Doctor.
“Don't be horrible, Doctor,” said Clara.
Iris laughed. “Oh, I like this one. I never thought much of your taste in women but I do like this one. How's the wife?” she asked.
“Dead,” said the Doctor.
“Oh, poor thing,” said Iris, not sounding very sincere. “I expect you want something to take your mind off it, such as helping me with the bus.”
The Doctor looked pained. “Fine, I'll take a look at it.”
“I didn't come here on purpose, you know. Do you think I'd visit Earth's moon intentionally? It's awful, there's no atmosphere.”
Clara laughed, if only because the Doctor didn't.
Surprisingly, the bus was slightly smaller on the inside. It was decorated in a quite cheery fashion, though, and it looked more comfortable than much of the Doctor's TARDIS. Clara sat on an overstuffed armchair while the other two worked.
Iris was trying to start a conversation with the Doctor. “What have you been up to, dearest?”
“Things,” he said, vaguely. “And stuff. Things and stuff.”
“Have you found Gallifrey yet?”
The Doctor finally looked at her. “How could you possibly know about that?” he asked sharply.
“I shouldn't say,” said Iris rather coyly.
The Doctor sighed irritably and went back to concentrating on the bus's innards.
“Have you found out what's wrong with it yet?” asked Iris. “It didn't take me anything like this long.”
“Why do you need me if you already know what's wrong?” demanded the Doctor.
“Second opinion, of course. Even I've been known to make mistakes now and then.” Iris ignored the Doctor's angry look, picked up a pile of knitting, and headed to the back of the bus.
Clara followed her. “I have a Time Lord question.”
Iris looked up from untangling her knitting. “Yes?”
Clara checked to see that the Doctor wasn't listening and asked “If he's brand-new, why does he look old? Shouldn't he regenerate younger? He used to be young. I mean, he used to look young.”
“Oh,” said Iris, “a young one. Which one did you have, then? Was it the hipster? Or the one that looked like a vet?”
“Um, hipster, I think.”
“I expect he flirted with you,” said Iris knowledgeably. “He does like flirting with his humans. Personally I think he should see a therapist about that.” She shook her head. “Men are mere mortals who are not worth going to your grave for.”
“Are you quoting Shirley Bassey?”
“She's a wise woman.” Iris smiled triumphantly as she undid an especially vexing knot in the wool.
“Iris!” called the Doctor from the front of the bus.
Iris called back to him, “You can cope on your own for five minutes, my love. Don't be clingy.” She turned to Clara. “He's very needy, don't you find that?”
“Iris!” the Doctor called again. He stood up, wiping his hands on his trousers.
Iris and Clara made their way to the front of the bus, knitting cast brutally aside as less interesting than whatever was about to happen.
Iris glanced at Clara before addressing the Doctor. “You might want to be delicate about it, since there's a human present.”
“Your bus is in heat,” he said without preamble.
Iris clapped her hands over Clara's ears. “Yes,” she said.
Clara shook Iris off. “Wait, what? It's in heat? Like an animal?”
The two Time Lords looked at her as though she were a bit stupid, and nodded.
Clara looked at the Doctor. “Can your one do that?”
“It's always been a possibility,” he said vaguely. “Iris,” he said, “why didn't you have it fixed? Don't you know the sort of trouble this could cause?”
“I might ask you the same questions,” said Iris primly.
The Doctor blushed. “Yes, well, I suppose there's no point in recriminations.” He scratched his chin. “We need to think of a solution.”
“I was going to go with the obvious one,” said Iris.
“You're not impregnating my TARDIS,” said the Doctor.
“She's too young to be starting a family.” He took Clara by the hand and headed for the door of the bus with her in tow.
Iris didn't move. “Don't think you can run off and avoid your responsibilities.”
“I don't have responsibilities,” he said as he opened the door. “I try to avoid those as much as possible.”
Clara followed him as he stomped across the combined airshells back to his own TARDIS. “You can't just leave her,” she protested. “She's the only other Time Lord, that has to mean something.”
The Doctor ignored her and headed for the console. “You don't know what she's like,” he said, setting the coordinates. “She probably set all this up just to annoy me.”
“I don't think so,” said Clara, who admittedly didn't know one way or the other.
The Doctor pulled the dematerialisation lever.
He pulled it again. Then, without a word, he turned and walked back to the outer doors.
Clara stepped in front of him. “What's happening? Is the TARDIS broken?”
He moved her out of the way and left the TARDIS, leaving Clara with no alternative but to follow him like a lost puppy. She really hated when he did that.
She caught up with him as he stepped onto the bus.
Iris was still standing where they'd left her. “Now,about this impregnation business...” she began as though nothing had happened in the interim.
“Iris, under no circumstances am I going to impregnate you,” said the Doctor.
“Not me, my TARDIS.”
“You want me to impregnate your TARDIS?” he asked, confused.
Iris sniffed. “I don't know what you get up to with yours, but no.” She gestured around the bus. “Just park them inside each other and let nature take its course.”
“Don't be ridiculous. They hardly know each other.”
“That would be why yours won't budge,” said Iris, knowingly.
The Doctor waved a hand. “It's just a crush, she doesn't want to commit to anything serious.”
Clara felt the need to say something. “You can't breed spaceships,” she said, in case the other two had forgotten this important detail.
Iris looked at her with something that seemed horribly like pity.
“Even if you had a boy one and a girl one -”
“They don't have a clear-cut binary gender system,” said the Doctor. “They're TARDISes, not cats.”
“But it does take two to tango,” added Iris.
Clara thought about this for a moment. Then she said, “Can't you give them a contraceptive?”
“Good idea,” said the Doctor, sarcastically, “We'll just nip out to the chemist's for a condom that fits a double-decker bus.”
“I was only trying to help,” said Clara.
Iris patted her shoulder. “Don't mind him, he's trying to deny his own lusts.” When Clara looked blank she added, “We're the only two left, you can imagine what he's thinking.”
“I'm thinking nothing of the sort, Iris!”
“Good, I've got better things to be getting on with.” She smiled Shirley Bassey's most charming smile. “Shall we put on some mood-lighting and retire to a safe distance?”
The Doctor wasn't going to be won over so easily. “Where would we keep it? Who'd look after it? Who'd clean up when it spilled it's internal dimensions all over the place?”
“We can burn that bridge when we come to it,” said Iris soothingly.
“Iris,” said the Doctor, “forget it. We're not breeding them. There's nothing you can say to change my mind. It's not happening.”
Iris produced a pack of cigarettes from her cardigan and lit one. “That wasn't bad,” she said. “Should we send out for pizza?”
The Doctor waved the smoke away. “Only you would get your jollies from something like this.” He looked slightly sick.
Clara watched the two TARDISes shift back to their usual separate shapes. “Is that it? Is one of them pregnant now?”
“I hope not,” said the Doctor. He glared at Iris. “This is all your fault.”
Iris spread her hands in a gesture of innocence. “We wouldn't be having this discussion if someone hadn't lost Gallifrey down the back of the sofa.” She dropped her cigarette, stood on it to extinguish it, and walked over to the bus. “There, there,” she said, patting it, “it's not your fault his TARDIS is a harlot.”
The Doctor didn't dignify that with a response.
Clara insisted that they should part on less-awful terms, if only because Iris was a Time Lord and the Doctor should be grateful that she wasn't dead or hidden in some other universe.
The Doctor offered Iris his hand. “I suppose it was nice to see you again,” he said grudgingly.
Iris ignored the hand and hugged him instead. “Of course it was!”
When she finally released him the Doctor took a step away from her, but it was quite a small step and he didn't actually run away. So that was something.
Iris fixed her hair and said, “I suppose my work here is done.”
Clara just wanted to clear up one small issue. “Iris, how did you manage to not... whatever it was that happened to all the other Time Lords?”
“Oh,” she said breezily, “I was the one that did it to them.”
Clara looked at the Doctor. “But...”
“It's best not to argue with her,” said the Doctor.
Iris nodded. “He's always stealing my adventures and pretending they're his own. Even that quite boring one with the Ice Warrior on the Russian submarine.”
“No,” said Clara, “I was there for that, that was definitely one of his.”
Iris laughed. “Oh, Clara, how innocent you are!” She climbed onto the bus and waved at them from the driver's cab.
“She's really odd,” said Clara as she watched the bus drive off into time and space.
“Finally someone sees it!” cried the Doctor to an uncaring universe.
And that was that.