The First Order did not attack with lightsabers or spacefaring weapons. They deployed drones: mindless, remotely piloted drones that detonated the small fighter craft and then ravaged the ruins of the Sith fortress on Mustafar.
Luke, being Luke, had needed little time to dig his way out of the rubble with aplomb. But it had taken little more time to confirm that their supplies, and their way out, were all lost. Without backup comms or a hyperspace amplifier, all they could do was wait.
The tragedy was that Mustafar was only too rich in history, or at least, Vader's stronghold had been. If their itinerary had only allotted a day or two, Leia and Finn and the others would have grown concerned. But they'd budgeted weeks to go through the archives, seek out holo-recordings and Force eddies, perhaps even investigate what hardy life-forms flourished in the inhospitable world. By the time their absence was concerning, it would be too late.
Rey squinted, outstretching her hand as she focused on another rocky island amid the lava flows. She guided it to the left, slightly, then a bit further against the current, until it came in line with the others she had manipulated to form a precarious bridge.
There was nothing different on the next landmass. No allies, no food, no water. But it gave her some measure of control. Even as her body wasted away, she felt stronger in the Force than ever.
"Is the dark side strong here?" she asked, turning from the islands to where Luke sat.
"It could be," he said, "if you were to seek it. Even I cannot completely forget its lure."
Even he, the selfless hero of the Jedi, or even he, who had cut himself off from the Force for years? "You know what I mean." When he made no reply, she went on, "Vader was here. Does that make the--the temptation stronger?"
"I don't think so," said Luke. "His presence can be felt here, of course, but it can be felt wherever there are Force-users he wants to speak with."
"I haven't seen any ghosts, not here."
"Maybe they haven't bothered. They'll get to meet you in the Force soon enough."
"How do you stand it?" She stood again, impatiently, adjusting the balance of each bridge rock.
"You're dying, and you act like you don't even care. Was your life that terrible?"
Luke shivered; so her question had cut deep. "Of course not. I regret that I won't be able to help Leia in her next fight. I regret that I never made things right with Kylo Ren. Most of all, I regret bringing you into danger."
"I chose to come too," Rey pointed out. "You don't get to take all the blame."
"Even so. It's easy--not so hard, I should say--to have faith when you've spoken with ghosts on a regular basis."
They'd swapped stories of growing up in the desert. Bit by bit, Rey had pieced together an outline of the young rebel who had flown with Rogue Squadron and escaped a trash compactor even before he'd wielded a lightsaber. "If only we had a steam attractor, a tempi module, a receptacle, and three or four support beams," he'd mused, standing in the wreckage of the castle, "I could probably rig together a moisture trap."
"Here's a beam," said Rey, trying not to splinter herself on half a plank. "Moisture trap?"
"I grew up on a moisture farm," he explained. "Some things you don't forget after collecting them every day."
"You farm water out of the air on Tatooine? Why would anyone live there?"
"That's a bit rich coming from you," he said, but he'd been smiling, and Rey didn't need the Force to feel the warmth in his voice.
"On Jakku there was interesting scrap," she had offered, in turn, the next evening. "I found a helmet from Dosmit Ræh, one of the Tierfon Yellow Aces, and took it everywhere. I thought she had a pretty name."
"The Yellow Aces!" said Luke. "I met a couple officers who'd been based out of Tierfon, later. That was long after they'd abandoned it."
So he had not known Dosmit. Maybe that was better, not to be mourning the loss of some long-forgotten comrade all over again.
Rey leapt onto the first island, then thought better of it--Force or not, her knees were not ready to fly. She slowly glided back to the shore and stepped back. "If you die before me," she said, "I'm scavenging you too." The plank could serve to hold something over the rivers of fire.
"I wish you could," said Luke, and there was something serious to it behind his equanamous humor. "When Yoda and--" he checked himself, "Obi-Wan died, even their bodies dissolved into the Force. Nothing left but a pile of robes."
"Is that just a Force thing?"
"I don't think so, although I haven't seen the remains of too many Sith lords either."
"Well, I'm not an official Jedi, so maybe I'll leave a corpse."
"You're every bit as official as I was," Luke pointed out. "And as Leia's next protege and the one after that will be, piecing together something new."
"Is that a compliment?"
"All I mean is that the Jedi are bigger than any one person or weapon. Vader's hubris wasn't enough to destroy them; neither was mine. Ren and Snoke's won't be, either."
Once again Rey felt a brief flash of anger that Luke had chosen to lock himself away on Ahch-To for so many years. What had the galaxy lost, without him? But that time, it was tempered by the maze of possibilities she saw unfolding from time's stream. Without his mistake, Poe Dameron would never have brought BB-8 to Jakku, and she might still be subsiding on the scraps of Niima Outpost.
As she had that day on the island, she opened herself to the Force, to the web of presences near her. There was Luke, enduring like a steady beacon; there, too, were a host of microbiota dwelling within them, part of whatever fate met them. Decay and growth, air and rocks and fire, the starless sky. All were part of the galaxy, as natural as the trees of Takodana or the oceans of Ahch-To, and all held in balance. The darkness within the Force she had feared was an anomaly that would dwindle out of existence, not a constant like death or change, or even her own human fear.
"I'm glad you're here," she admitted. "I wouldn't want to be alone."
"Me neither," said Luke, the desert child, the Jedi Knight, the long-lost brother.
She held him as he slipped through her fingers, first his dry flesh, and a moment later the cyborg arm that had, too, been part of his living self. Then, carefully, she retrieved the lightsaber they had shared. She set it on high ground, where it might shine long after she followed him, not knowing that on the same rocks another griefstricken warrior had gathered that weapon to pass on to another generation.