Author's Note: So, if you're reading this, you ought to have at least a working knowledge of starfleetrambo's excellent Demonic Guardians AU. If you do not, I suggest you clear up twenty minutes or so (depending on how fast you read) to dedicate to the canon comics (bit . ly / 2ib9NFz), at the very least. Then come back here.

Okay! Ready? This takes place after the events of the official comics, although not by much, hence Bill's human form and Dot's (completely unjust) lack of the same.

I have my own idea of the physiology of demons in this universe, but I'm deathly allergic to disgorging specific details when they aren't even pertinent to the story. The best I can tell you is that it will be alluded to! Briefly! By someone in no condition to be giving lectures! So, uh ... SURPRISE? 8D

Also contains spoilers about the Author in this very chapter. Actually, don't glance down, because it's, like, right there. So if you haven't watched that far ... what the heck are you doing reading fanfiction?

"The Author—that is, Great-Uncle Ford—he says he encountered one of the Native tribes indigenous to the Pacific Northwest, up around Canada actually, and they had a name for it." Dipper squinted at the scrawled letters, a little uncertainly. His left leg jiggled restlessly in place, the only outward sign he gave of his extreme inward agitation. "The … darn it, Great-Uncle Ford, would it kill you to write on a flat surface now and then? … okay, um. I think they called it the … uh, 'the God-killer.'"

Dot groaned. "Oh, charming. What an absolute delight."

"Yeah," Bill agreed, tapping his cane on the cavern floor in a frustrated tattoo. "Talk about reassuring, huh? Sheesh, kid! We're demons, and you expect us to fight something called the God-killer? I dunno whether I oughta be touched you think us so capable, or just a leeeetle sick that you want us both to die horrible, screaming deaths."

"Wait," Mabel broke in, glancing up from her candlelit knitting to look uneasily at her guardian demon. "I thought you guys were immortal? I thought that was, like, a given with demons. Dipper said you were just energy, and energy can't … can't die, right?"

There was a moment's perfect silence.

"Right?"

Dot Matrix, a one-eyed Masonic symbol drifting in mid-air, glanced at the human girl that had been assigned to his care at the moment of her birth. "Well …"

"The God-killer," Bill repeated. It was not an argument, he felt, that could be much improved upon with further rhetoric. Then he took in Mabel's anxious expression and sighed, kneading his brow with one gloved hand. "No offense, Shooting Star, but I don't think this guy got that name on account of his killer-delicious baked goods. What a disaster. Fuckin' Christ."

"Bill," Mabel scolded, stern and sharp.

Bill considered telling Mabel exactly where she could go jam her G-rated language, repeatedly and with varying rhythms of force—and then his sightline drifted a little further left, where Matrix still floated, his eye narrowed as he glared at Bill. Bill sighed and lifted his hands, palms upward.

"Fine, geez. Killing the God-killer. The God-killer," he couldn't help but stress, one last time. "And we're demons, did I mention that?Oh, this is gonna be a blaaast!" We're gonna die. Every single one of us. For fuck's sake … the shit I do for power.

"Uh oh," said Bill faintly. This was not well-planned. He could see himself reflected in the beast's eyes, from the tip of his top hat to the toes of his shiny wingtips. He could also see a lot of other things—lots of goddamn pine trees, fields of goddamn pine trees, and by now he hated pine trees just so goddamn much—but seeing a reflection of your entire body, reduced by relative comparison to a tiny yellow pinprick, in the eyes of something that is perfectly capable of smearing your electrons across a vast and bleeding void of agony … well, turns out that's a tad hypnotic.

Then, because Mabel wasn't there to rebuke him and Bill appreciated the little freedoms, he leapt to his feet and lunged for the God-killer fist-first, snarling, "Take my regards straight to Hell, you ugly skyscraping motherfuc—!"

"—HHHH! AAAHHHHH! Aaaaaaaahhh—hh … hhhhh … huh?"

Dipper stared wildly in all directions, wrapping his arms tightly around his torso and trying to choke back his tears. (The attempt, while valiant, failed miserably: Dipper wept like any twelve-year-old boy, coughing and spluttering wetly as snot dripped from his chin, soaking his shirtsleeves—comely crying was for the strapping, handsome leads in movies, which he most definitely was not.)

Nothing made the least amount of sense—he remembered running, and screaming, and the God-killer picking him up; he remembered the thing lifting him up to its immense, mind-defeating face, and that the speed at which he'd flown so high into the atmosphere had briefly extinguished his consciousness altogether before his blood pressure was able to catch up.

He remembered feeling intensely grateful that Dot had teleported Mabel safely out of the monster's reach, even as he burned with hatred and no small measure of anguish that Bill Cipher had not done the same. What was the use, he'd thought, of having a demon for a guardian if it got you killed?

Of course, he was aware (and had been for months) of Cipher's obsession with his own bid for world domination, and so he thought that Cipher would probably have been pretty bummed if Dipper had died, or been eaten, or macerated into a paste by some Lovecraftian horror. That wouldn't have made him, Dipper, any less dead, however; it was a cold comfort at best.

As the God-killer's fingers had wrapped tightly enough around Dipper to bruise his ribs, pride had kept Dipper from screaming for Cipher—well, pride and a troublesome lack of oxygen, as he ascended several thousand feet into the air within moments, his gut and his brain madly swapping places—but Dipper hadn't figured it would really have done any good, even if he'd had access to all the air in the world. Cipher had complained enough about the whole venture that Dipper suspected the demon hadn't even stayed in the same hemisphere once Dipper had voiced the horrifying revelation that the valley they were in had been, not just a footprint, but a very recent footprint.

Then … then he had woken to the reality of pine needles digging into the raw flesh of his skinned palms, and Dipper had opened his streaming eyes to find that he was sitting sprawled on his butt in the dirt, safely on the ground. Around him, branches creaked in a rising wind, and he was completely alone. The woods glowed silver, awash in moonlight, and Dipper felt a scream of fear and frustration and total incomprehension building in his throat, choking him, hot as bile—or maybe blood.

Dipper rolled over and was noisily sick in the dirt for several minutes.

Just as he was wiping a shaking hand over his mouth, fighting to collect enough of himself that he might have been able to summon the energy and presence of mind to even think about standing back up and, eventually, trying to find his sister and her demon, there came a blinding flash of light. The concussion hit a full five seconds later, and Dipper lurched forward into his vomit as though shoved bodily from behind.

A nuclear blast!? Dipper wondered wildly. But who would know enough about the weirdness of Gravity Falls, yet have enough political clout, to be permitted to store warheads anywhere within or near the Oregon/Washington state area? Not that it wouldn't have come in handy a few dozen times Dipper could think of, right off the top of his head … he sat up, slowly and tentatively, before wiping his face with an involuntary little sneer of disgust. My flesh isn't sloughing off my bones, at least; so that was probably not nuclear. While it didn't really clear much up, at least 'not nuclear' was a start. As well as a step in the right direction: Dipper was pretty attached to his flesh, after all.

"Dipper!"

"Mabel?" Dipper looked up so fast his neck creaked.

Here came his sister, astride a beautiful, trotting charger, its pure-white hide all but gleaming in the moonlight. Its mane and tail floated back in a slipstream that did not seem nearly sufficient enough for the purpose, silken as ribbons, snapping like banners. Mabel's hair, cascading in curly waves down her back, completed an image that rightfully belonged on the back of a Lisa Frank trapper-keeper.

Dipper's eyes narrowed and his recently-emptied gut stirred warningly in a spasm of the reflexive loathing reserved by all twelve-year-old boys for the sort of unicorns that invite prepubescent girls on magical journeys, its deepest reaches unsapped in Dipper despite a childhood spent suffering from daily near-fatal overdoses of glitter, dolphins, and rainbow-spotted leopard cubs.

"Is that a horse," Dipper said. His flat tone made it a statement, not a question.

Mabel grinned foolishly. "D'you like it? Dot called it up for me from … somewhere. I figured it was safer not to ask."

"It's very … white," Dipper allowed judiciously. Even though his demon hadn't conjured up a pony for him to ride out of the line of fire, there wasn't any point in dragging down Mabel's mood … too much. "Grunkle Stan will never let you keep it," he pointed out, a cynical Cassandra.

"Oh, I know," Mabel said cheerfully. "It's just a rental, y'know?" The horse came to a well-trained stop just short of where Dipper sat in the mud, half-crouched over his own emesis. Dipper glared at it.

After a little awkward wriggling, Mabel slipped down from her steed's neck, and offered a hand to Dipper. He accepted it with ill-grace as she asked, looking around curiously, "Where's Bill? Did you see that weird flash? It made Dot disappear altogether. Poof!"

"Yeah," Dipper answered the easier of her questions, and the only one with a concrete answer. "I thought maybe it was nuclear, for a little while. Like Hiroshima. If it made your demon freak out, though," and he released his pet theory with only a small pang of regret, "it probably wasn't."

Mabel slung a companionable arm around Dipper's shoulders. "Well, look at it this way, bro-bro. If it had been a nuclear explosion, we'd all have been poofed."

Dipper couldn't help but grin at this line of pure practicality. "You've got a point."

"But if I keep my hat on, no one will notice!" Mabel crowed triumphantly in his ear. "You're losin' it, Dipstick! You walked right into that one! Right into it!"

"Yeah, yeah," Dipper agreed, still grinning. "You got me, Mabel."

His sister turned abruptly to look at him, her mouth serious but her eyes glinting wickedly. "Wanna drive?"