It occurs to Mel, during the fifteenth lap around a track on an alien planet, being pursued by aliens carrying alien weapons with alien intent, that things are getting a bit bizarre.
"Doctor," she says. When he doesn't reply, she glances back and realises that he's fallen behind. "Doctor, come on!"
The Doctor speeds his pace, but she isn't entirely sure if it's due to her words or to the spears their hosts are waving. "I'm getting too old for this," he mutters.
"You?" Mel gives him a reassuring pat on the shoulder, undeterred by the glare he shoots her in return. "Never!"
"Mark my words," he begins, sounding remarkably long-winded for someone so evidently out of breath.
Mel adopts a carefully studious expression as he starts in on his speech, and lets her mind wander, remembering back to school, to running the track alone in the last moments before nightfall, everything silent and still and making sense, like numbers, like command prompts, all lining up into one destination that goes round and round. She decides it's a fairly good indication of her life with the Doctor - round and round they go, never stopping.
Of course, she's not sure the comparison is meant to be taken quite so literally.
"-and that," the Doctor finishes, with a wave of his hands, "is why we should visit Ganermalion VI."
Mel fumbles for the last few strands of his monologue. "The sloth people?"
"Not a chance of them pursuing us around in circles!" The Doctor smirks. "No, they'll just sit on their chairs and watch. Oh, there's the small matter of their remote vapourising satellites, but-" He pauses. "Well. Maybe it's time for another jaunt to your planet, Mel."
"Wise choice," she says. "Come on, then."
Ignoring his puzzled glance, she slows her pace slightly, cooling down, and jogs off the track.
He scowls as she stops altogether, stretching her legs. "What are you doing, Mel? They'll catch up to us!"
Just as he says it, the mob of aliens streams right past and clatters its way around the bend, following the track.
"I don't think so," Mel says mildly, and grins. "Back to the TARDIS, then?"
"But-" The Doctor waves a hand at at the jogging aliens. "Do you mean to say we only ever had to leave the track to get them off our trail?"
"Of course," says Mel, and shrugs. "Thought we could do with a bit of a good jog."
And oh, he scowls again and makes faces and stomps around a bit and pouts, but she's used to that. He's predictable, like any computer system, like tracks spinning in circles, and she knows he'll come round in the end.