A man and a woman made their way across the countryside toward the looming remains of a colossal clock tower fashioned almost entirely out of platinum. The woman, an attractive, dark-haired American named Peri, walked with a gait that suggested extreme fatigue, just as her white T-shirt and blue shorts spoke to the day's stifling heat.

Beside Peri walked her friend, the sixth incarnation of the Doctor. Nothing about him suggested that he was tired, or that the day was hot. He walked with a triumphant spring to his step, and, as usual, he sported an absurdly polychromatic frock coat over a heavy white shirt and a colourful vest. As he walked, he tried to engage Peri in conversation about the local flora.

The Doctor's efforts failed. "I'm tired," said Peri. "And I'm too hot to think about plants."

"Fine," replied the Doctor. "Botany is your passion, not mine."

Peri refused to let the Doctor bait her, so they walked on in silence.

In time, the two of them reached the ruined clock tower, and made their way into its gloomy interior. Peri sighed with relief as they escaped the direct scrutiny of the alien world's red sun. The Doctor fished a small flashlight from one of his pockets so they could see where they were going. As they made their way up spiralling stairwells and through the rusting innards of the gigantic clock, the Doctor said, "You know, I really should repair this thing someday. It's pity to see such a fine timepiece in such sorry shape."

Huffing for breath, Peri said, "Someday, but not today, Doctor. Today we're getting off this miserable planet ASAP."

"Peri, you really must learn to curb your enthusiasm."

"Sarcasm is no substitute for a sense of humour, Doctor," retorted Peri.

The Doctor had a retort of his own. "And I say to you that humour is no substitute for sarcasm. You're in too sour a mood to enjoy the sweetness of my natural wit."

"Sour?" exploded Peri. "Sour? Sour! Not two hours ago, I was almost eaten!"

"Peri, those magnificent dervorxes would never have eaten you," replied the Doctor.

"They could've fooled me."

Not long after Peri said that, they came to the TARDIS, a time machine improbably disguised as an emergency phone booth. Once inside the control room, she said, "Sometimes I really miss Frobisher. His abilities certainly could've come in handy back there."

"I thought I handled things quite nicely," remarked the Doctor indignantly.

"You did," admitted Peri. "But Lord Servinode's pets came much to close to eating me for comfort."

"Peri, I've already told you that those dervorxes wouldn't have eaten you," snapped the Doctor. "They might well have ripped you to shreds, but they would never have eaten you. You would've been quite toxic to them."

"Same difference," retorted Peri. "Either way, I would've been dead."

"Point well taken," conceded the Doctor. "Well. Now that we've set matters right on Ubolle Four, where should we go now?"

"I don't care as long as it's someplace safe and quiet," answered Peri.

"I know just the place!" declared the Doctor enthusiastically. "The planet Jelmach! I visited it after we temporarily parted company in New York, about forty years ago. I..."

Peri blinked in astonishment. "Did you say forty years ago?"

"I did," replied the Doctor. There was a bewildered expression on his face. "Why do you ask?"

"Doctor, just how long was our separation, from your point of view?" Peri had known of coarse that some time had passed for the Doctor before their reunion, during which he had befriended Frobisher, but she had always thought of it in terms of months, not decades.

The Doctor answered, "I suppose about fifty years."

"You forget about me for fifty years!" roared Peri.

"I didn't forget about you," replied the Doctor sharply. "You were safe, back home in essentially your own time. I don't see what you're so upset about. It's not like I left you on some dangerous alien world or away from your proper era. Nor did much time pass for you before we were reunited."

"But you waited fifty years before you came looking for me!" retorted Peri. "That's like two generations! I thought our friendship meant something to you! But it must not, if you could just let so much time pass without even visiting me!"

"Peri, you don't understand what you're saying!" protested the Doctor, sounding genuinely hurt. "You simply don't understand."

"Then explain it to me!" exclaimed Peri. "Help my poor human brain understand why avoiding me for half a century wasn't a snub!"

Not meeting Peri's gaze, the Doctor replied, "You're right. I made our separation seem inadvertent, but it really wasn't. And, as you suggest, I was avoiding you, but not because I don't value our friendship. In fact, the opposite is true. It's not an easy thing to talk about, but in all likelihood I'll survive you by centuries, perhaps even by thousands of years, if I can start managing to get more duration out of my remaining lives. That being the case, from my point of view, our time together will be over all too quickly. So I thought that if I spent some time away from you, I could stretch out the time remaining to us. I didn't imagine that doing so would have hurt you. I'm sorry."

Peri's eyes watered. Despite everything that the Doctor had done for her, she had still underestimated the depth of his friendship with her. She wanted to hug the him, but she knew better. That just wasn't his way. So she just said, "I'm sorry too."

After a few seconds of awkward silence, the Doctor asked, "Well, are you ready for Jelmach?"

"You bet," replied Peri with an enthusiasm she didn't really feel. Their latest adventure had taken a lot of her, but she didn't want to disappoint her friend. She knew now that the Doctor was well worth the effort.