Author notes: I've only seen Rogue One once, and I haven't gotten the novelization yet, so some of the dialogue might be messed up, but I did my best based on my memories, so.. yeah, don't be too harsh in dialogue accuracy, please :D
Another thing: The perspective shifts a bit when one person falls asleep, because what the other person does in that time is important. It starts out in Cassian's perspective.
I stumbled back as the ramp closed, Jyn standing in front of me. She turned and glared at me, hatred emanating off her in waves. I tried to act normal, putting away my blaster rifle and walking toward the cockpit. I feel a hand grip my arm, and turn to face Jyn. "You lied to me. To us. You were going to kill him," she said, her voice growing thick with emotion in the last sentence. I almost sigh. I knew this conversation was coming. Of course it was coming.
"But I didn't kill him," I reply, crossing my arms.
"That's beside the point! You had every intention of doing it!"
"At the end, what matters is what I ended up doing. And I ended up not killing your father. I disobeyed my orders." That's the important bit, right there.
"Oh, so your orders were to kill an innocent man and lie to his daughter? And you just blindly followed them until you have to actually kill him? Is that it?" My silence is my reply. "Then you're nothing better than a stormtrooper." The words stung. Her logic made sense, but to call me a stormtrooper? Low blow, Erso. Low blow.
"I am not a stormtrooper," I say, trying to keep my voice quiet, intimidating.
"Oh yeah?" She looks like she's about to continue, but I cut her off before she has the chance.
"I have been in the Rebellion since I was six years old. This is the only life I have ever really known. Following orders. Doing whatever they tell me. But Jyn, I disobeyed my orders today, for the first time. I had the rifle aimed at him. My finger was on the trigger. I had every opportunity to kill your father. But I didn't."
She stands there, dumbfounded, her mouth agape. Then, she's about to say something when K-2's voice calls from the cockpit, "If you don't mind, Cassian, I could use a co-pilot."
"Coming," I say, glad for this excuse to turn away from Jyn.
I drag my hand over my face. It's been a really long day. First Jedha, then Eadu, then the argument with Jyn. Time to go down to the bunks and.. KRIFF! The Imperial ship only has four bunks. I know I went down earlier and tossed my jacket on one, but when I go down Jyn is lying face down on the bunk. My jacket lies discarded on the floor beside it. The rest of the bunks are occupied by other members of the crew.
Ok, I have three options now. Floor, co-pilot seat, or kick Jyn out of the bunk. Much as I would enjoy the third option, I decide against it. The girl has just seen her father die in her arms, and had to endure her mentor of six or seven years being killed. I'm giving her a break, for once. Plus, we'll probably have to work together tomorrow, and it's better to work with a well-rested person than a person who didn't get enough sleep because you kicked them out of their bunk.
I pick up my discarded jacket, and ball it up into something that resembles a pillow. I sit down and lean my head on the wall opposite the bunks, placing my make-shift pillow under my head. If I tried to sleep in the co-pilot seat, K-2 would just keep me up all night with his jabbering. At this point, floor is the best option. I'm so exhausted from today that the minute I close my eyes I fall into a deep sleep.
-JYN'S PERSPECTIVE-
I knew I should have used the bathroom before sleeping, but I was just so tired.. On the way back to my bunk, I trip over something lying on the floor. Upon closer inspection, I see that I tripped over feet. Captain Andor's feet, to be more precise. When I look up, I see him sleeping, his head leaning against the wall, with the jacket I tossed off my bunk bundled up under his head. I finally make the connection that that jacket had been his, and I had basically stolen his bunk when I claimed it for myself. I felt a flash of guilt, followed by confusion. Why didn't he just wake me up and make me sleep on the floor? I may never know, but the least I can do is let him sleep in the bunk, right?
I slide my arm across his back, lifting him up slowly. Apparently-thankfully-he's a deep sleeper, as even as I pull him over to the bunk he doesn't stir. I lie him down on the bunk, and pull the sheet over him. He reacts immediately, snuggling into it and almost making me laugh at how much he resembles a small child. I turn and sit on the floor, taking the place he was just occupying, and fall into an uneasy sleep.
-CASSIAN'S PERSPECTIVE-
I jerk awake. The first thing I notice in that I'm now in a bunk, even though I fell asleep on the floor. The second thing I notice is that Jyn is now sleeping in the spot on the floor where I fell asleep last night. The third thing is that my head is aching from me hitting it on the bunk above when I woke up so quickly. The fourth thing is that K-2 is poking at my arm, saying in a bored voice, "Wake up."
"What's going on, K?"
"We are about to drop out of hyperspace. Having a co-pilot can be useful sometimes. Especially if I'm the one waking everyone up."
I groan. "I'm getting up, I'm getting up.." As I walk towards the ladder that will take me up to the cockpit, Jyn pops back into my mind. I hesitate, and turn to look at her. Had she been the one to move me to the bunk? I shake the thought out of my head. That's impossible. She hates me. I turn and climb up the ladder, rubbing the sleep from my eyes as I sit in the pilot seat.
Five minutes later, the rest of the crew are standing in various degrees of awakeness getting ready to land on Yavin 4. I get up and let K-2 sit down in the pilot seat, and step into the galley where everyone else is. "We're about to land on the Yavin base. I advise you to do what people tell you and to not aggravate anyone."
"Solid words of advice," Jyn says sarcastically. I fix her with a sharp glare, then turn and step back into the cockpit, sitting down into the co-pilot seat.