In about five billion years, the sun will go out. It won't be immediate, like the extinguishing of a candle. It will be an astronomical process, and therefore slow. There won't be anything mystical about it. All that will happen is that the sun will run out of fuel, give one last gasp of expansion, and then sink into darkness.
In other words, he'll get tired, and someone else will have to take over and start again. The gods have known this from the start. It's silly to expect one sun god, or even one amalgamation of many sun gods, to keep journeying across the sky forever. The big question remains, though. Who's going to take over when he's done?
On a hunk of rock spinning out into the distance with no sun in the sky, an animal lopes across the cold and barren waste. This is impossible, of course. There's barely a hint of atmosphere, and there's never been life on this moon. Nevertheless, the animal runs across the cratered landscape that, if you squint, looks a bit like a particularly inhospitable stretch of desert. He's not an animal that would have been recognized by most humans, back when there were humans (and that was a very long time ago). Actually, he looks a bit like an aardvark, and a lot like a dog, but not quite like either.
He's wounded and tired, because he's been running for a very long time, sometimes across interstellar distances, and of course he's been fighting for a lot of that time, too. There's something in his mouth. Since he's really quite dog-like, it shouldn't be surprising that it's some kind of ball. It's small and black and looks like it's been badly burnt for some time now. But he's still holding onto it very tightly. Some metaphor about the world depending upon it might be appropriate here.
The dog-thing runs along the plains of the lifeless moon for what might be another few eons or maybe just another minute, turning his head here and there to check that he's not being followed. Finally, he slows to a halt, panting around the ball in his mouth. At last, after so long holding it that it might as well be part of his body, he spits the ball out of his mouth and watches carefully as it rolls a little ways along the barren landscape, leaving a small trail of soot as it goes.
He looks like he wants to say something. Of course, an animal talking is impossible, but so is an animal being here in the first place, and he's an impossible sort of animal in any case. He opens his mouth to speak, then closes it. The vacuum swallows up any words he might say. After a thoughtful moment, he crouches in the moondust and begins to scratch a word into it with one steady paw. He moves with careful deliberation, and all the ceremony of it makes it clear what he's doing: he's naming the moon.
The animal finishes scratching his word into the dust and steps back. In front of him, the landscape now reads as follows:
He smiles around sharp teeth and a lolling tongue. "That's settled, then." He can talk now, because there are two named things in the world now: him and the moon. That's how many you need to start communicating. "You have a name. It's a good one--it'll be even better if I can get another moon to follow you in your orbit. Then you can be a proper cosmic Nutsack for me together. And nobody will ruin you this time."
The animal admires his handiwork for a moment longer, and then he says, "So you're Nutsack. I'm Seth." He's so busy introducing himself that he doesn't notice something approaching in the sky. "We have an important task ahead of us now that I've finally shaken Apophis." The thing in the sky comes closer, and it becomes clear that it's a kite. Not the kind of kite children fly, or flew once, when there were children, but a bird. "It's called creation."
The kite lands next to Seth. "What would you know about creation?"
"Oh," Seth says. "It's you, sister. Where've you been?"
"Doing my duty," says the kite, who is named Nephthys. "Guiding the last stragglers through the Underworld."
"I don't know if you noticed," Seth says, "but I've been doing my duty, too. It's been a real pain. There isn't any barge of the sun left to defend, but I still had to keep the remnants safe, and Apophis just never seemed to get tired."
"He'll be back soon enough," Nephthys says. "We should find Osiris and Isis so they can start Creation again."
"But not Horus?" Seth asks hopefully.
"We'll find him, too," Nephthys says, much to Seth's obvious disappointment. "But right now, it's best we find my sister. She has the magic for it."
"That's not fair at all," Seth says. "A world created by her magic would be a tangled, cunning mess, and if I let her obsession with our brother color it, it'll all be dead, too. The answer's simple. I got here first." He nudges the little black ball with a paw. "And I carried the sun all this way. I'll make the new world."
"You named this place 'Nutsack,'" Nephthys points out.
"You can't tell me that doesn't turn you on a little, sister," Seth says with a suggestive shimmy of his brows. "It honors Mother and it's descriptive."
"Don't you usually prefer to honor someone by destroying something of theirs?" Nephthys asks.
"There isn't anything left to destroy," Seth says.
"You have a point there." They sit in silence for a little while, the bird and the dog-creature, before she speaks up again. "What kind of world would you create, brother of mine?"
"It would have better storms," he says immediately. "Solar flares wouldn't just make the magnetosphere dance around a little. They'd make great storms tear across the land. If I controlled the sun, that is."
"That's why you don't control the sun," Nephthys says.
"I do now," Seth reminds her. "People would learn, you know. They'd build better houses. They'd build themselves better. And then when Apophis came knocking, he'd have nowhere to get in."
Nephthys says nothing at first, but finally she admits, "You do have a talent for turning destruction to the purpose of creation."
"I serve Ma'at, as do we all," he says. He's purely serious for the first time since he set foot on this moon. "Any new world will, if we make it. Even if it's a mess at first."
"It'll keep being a mess," Nephthys says.
"You're right, of course," Seth says, grinning wickedly. "I wouldn't have it any other way. I'm going to start now," he adds.
"You can't wait for our brother and sister?"
"Why bother? They might not even be alive. Maybe it's just us."
"No," Nephthys says. "I'd know if our sister was gone. She's out there, and since she is, so is our brother. Her magic and his command of the Underworld will come back to Creation when it's needed."
"And it'll make things a mess," Seth says.
"So will we all," Nephthys says. "We are the children of Nut, brother. We brought strife into the world."
Seth paws at the ground around the burnt ball that was once the sun. "And now we're going to bring the world into strife. Stand back." He doesn't wait for Nephthys to comply before he begins. He starts by urinating on the sun. Slowly, it begins to turn a brighter golden shade.
"How much do you have in there?" Nephthys asks.
"Don't act so surprised," Seth says. He's still at it. The sun is bright yellow by now. "I haven't even had a chance to lick my wounds. I definitely don't get to take toilet breaks while spending aeons defending what's left of the sun from Apophis."
"Your wounds will heal," Nephthys says. "We are still gods, after all."
By the time Seth is finished emptying his bladder onto the sun, it gleams gold and steams with heat. He crouches down and picks it up in his mouth. Then, with a great burst of force, he hurls the glowing ball up into the sky. Higher and higher it rises, until it reaches the firmament and sticks there. The sun is back in the sky.
"Not going to tell me how disgusting that was?" Seth asks of Nephthys as he finishes.
"I may be keenly aware of your flaws, brother," she says, "having spent an interminable time as your wife--but I am no hypocrite. It's at least as acceptable as masturbating the world into existence."
"Good," Seth says. "Because I can't do that very well. Some wounds don't heal, you know."
Even though it should be impossible in her current avian form, Nephthys makes a noise suspiciously like a snort. "You deserved it," she says. "Will you stop complaining about that now that you've been allowed a moon-sized Nutsack?"
"Not a chance," Seth says.
"What if I fetch another moon for you, to form a Nutsack together with this one?"
Seth grins. "I'll consider it."
In five billion years, the sun will go out. But it will not be long before the dust settles around another star. Creation will always begin again--
--no matter what you call it.