I kept my eye out for places to increase descriptions throughout, but I think this fic did a great job of that, especially the descriptions of Kylo. The overall structure and bigger-picture characteristics were all wonderful, so I stuck to more SPAG and phrasing-focused comments.

‘I wonder if you hadn’t tried to get me killed, so I’d wait for you in the afterlife. Or as a sacrifice. On some prophetical whim of yours. Like a true emperor, buried with his servants, spouses and pets. And now, now you’re just finishing your job… And of course, you don’t even have decency to make it quick.’

Great beginning. The breathless and feverish tone of Hux's narration is also excellent.

Except through his entire life, Ren had never really seemed to be so glowingglow as he did now, this pale face of his sunken in some darn corona of light, now.

^Some suggestions for phrasing

I like the juxtaposition of prince Kylo vs Hux with his very un-princely ! (One note, "crown prince" sounds more natural to my ear)

He’d managed to shelter in a huge building, looking like a temple or a tomb, (it looked like a temple or a tomb),...

^Phrasing suggestion

He wished for one of Jakku’s poisons, the one which brought nice sleep or pleasant fantasies, but he doubted Ren’d know how to make one.

^There's a few spots throughout the fic where you've used present tense instead of past, I've pulled one out here and corrected it in bold.

The ship dynamic was great, I loved Hux's constant internal calculations trying to explain Ren's actions. And the ending was a perfect fit to that overall dynamic!

Please let me know if there's anything you want me to elaborate on or if you'd like me to take a second pass to look for something in particular, I'm happy to!