Yellow submarine

 Prompt: a line from a song. I got "We all live in a yellow submarine"

1. How this line was conceived

John and Paul were on the top of the world, Their world, at least. They had trained for months, prepared meticulously, and after more than one moment fearing they were going to be forced to give up, they had made it. Top of the world. Top of the whole solar system really. Olympus Mons was the King of mountains, and more experts had been defeated by it than could pride themselves to have contemplated the red horizon, dotted with lit up domes, from the 25,000 meters of its peak. 

John pulled out the inflatable habitat to spend the night, its bright yellow exterior in stark contrast with the iron oxide that made up the bulk of the regolith, and that had laid down in a thick layer everywhere, even up here. They got in, turned on the portable MOXIE and the main controller, waited for the pressure to stabilize and removed their suits. Comms were bad at the moment, probably another solar storm. Good thing the habitat offered radiation shielding. 

– Did you ever stop to think about our life? - asked Paul.

– Yes, a few times - answered John, shaking the sticky, statically charged regolith from his suit.

– And what do you think about it?

– Pretty good. Wouldn't complain.

– Don't you feel trapped?

– Why? Plenty of places to go, the new vacuum tubes make it easy to reach any dome in no time.

– I mean, don't you feel we're locked in? In some place we can't escape?

– Oh don't start. We have plenty of free time for outdoor activity. Plus, the solar cycle is getting to its lowest, so we won't be riddled with CMEs for a while. We may plan the whole Tharsis tour? What about it?

– I don't know. I feel like I'm in a cage. Some jail at the bottom of the sea, going on and on without a real route or reason.

– A what?

– Take it as it comes: a yellow submarine.

– A yellow what?

– I don't know, it just popped into my mind, no idea what it is.

– Sounds like something from down the Valley.

– Let's get some sleep, those slopes are not that steep but can still be treacherous in the morning.

They got into their sleeping bags, and both dreamt of being in a very colorful, antique animation, where some implausible people with lousy haircuts and sad clothes were singing that mysterious line over and over. Strange dreams can come when you're on top of the world and your portable habitat has the tiniest of leaks.

2. An interaction changes the meaning of this line for the characters

They woke up with a devastating headache to the flashing light of the habitat alarm beacon. They soon detected the leak, and worse, they realized the habitat controller had used the whole production of their MOXIE to keep the habitat itself stable, without recharging their suits. They had nowhere near enough to breathe until the next camping spot on the way down. They sealed the pinpoint-sized hole with the patching kit and tried to bring up comms to get help. With the leak sealed, they thought, they could just sit tight and wait to be rescued. That meant losing their record (you need to go up and come down on your own for it to count!) but they could do it again, with the whole system following their endeavor. 

Comms came up with a lot of static. They were able to communicate their position (hard to misunderstand, top of Olympus Mons), but were puzzled by the response: "There's a yellow alert for meteors. we won't risk a team for a rescue that can wait".

– Yellow! - commented John.

– It's a sign! - sighed Paul.

– We are trapped! -  they groaned together.

– At least we won't need to eat each other. Plenty of meal bars left. - shrugged Paul looking in the storage box.

– Imagine - said John in an inspired tone. - Imagine those guys back on Earth, in those real submarines, under meters and meters of water.

– I can't even fathom meters of water…

– Didn't you watch the old movies?

– Yes, but still.

– It's the same for us, except we don't have water above us, only sky - Continued John.

– And CO2 that could knock us out in seconds.

– And radiation that could fry our DNA in a day.

– And thin, statically charged dust that could destroy our life-support circuits.

– What are we doing here?

– Good question. At times I feel like we're in the wrong place.

– Locked in without escape.

– Under a sky we shouldn't be seeing.

The emergency radio came up with a blaring siren. Static was still disturbing the audio, but they could still hear the alert turning blue. Icy rocks on their way. Everyone to immediately proceed to the underground shelters. They laughed. Their habitat was on the inner lip of the ancient caldera.

– If we're lucky, we may really see a sea, before it sublimates.

They took each other's hand, staring at the painstakingly slow raising of the needle on their suit reservoirs, and took comfort in singing that absurd line: "We all live in a yellow submarine".

The fact their channel was inadvertently left open made it so that the emergency crews heard them, and got caught by it, and someone turned on the general alert system, and soon enough each one of the 14,738 domes was resonating with the catchy melody and the desperate clapping of hands, while everyone wondered where was the ice going to fall.

3. Begin or end or both with "You are worth a love song, but there are no instruments worthy of capturing your soul"

– You are worth a love song, but there are no instruments worthy of capturing your soul - said John to his wife after the alert had ceased, the water had indeed sublimated under their eyes and a rescue crew had brought them back. She scoffed. His escapade with that stupid Paul guy was eventually over. She had never liked him, but they had been friends since long before she had met him, so that corner of his heart was not hers to claim. It itched like a mosquito bite. There had been an outbreak from a lab once, nobody could understand why anyone would bring the pests all the way from Earth, where they were confined like some fabled plague from ancient times. She knew, like everyone else in her dome, the itchy feeling was relieved only by a small cut in the skin. And a much larger cut would be required to allow the sudden glucose peak his cheesy line had caused her to painfully ooze out.

He had written her love songs, more than she could tolerate. Yet none of them had touched her heart. And then, that other guy had come while he was away in his months long "endeavor", and his songs were so much better, they resonated with her inner melody and made her shiver and smile.

– Oh dear, I hate to say it to you this way, but there is an instrument that captured my soul.

– Really? What was it? A guitar? A piano? A romantic violin? Trumpet?

– Oh, none of those. I shouldn't have mentioned it, I don't even know why I did.

– Tell me.

– Well… - she hesitated. - It's actually an organ.

– A church organ?

– Most definitely not – she chuckled.

– I don't get it.

– I know you don't. I do. And it's not yours.

He froze, his mind refusing to take the next, obvious logical step. He started to slowly clap his hands.

– We all live in a yellow submarine…

She echoed, unconvinced.