I couldn't sleep, so have this.

Buffy the Vampire Slayer is all about averting the end of the world. Always Coming Home is what happens after. I've looked around and there doesn't seem to yet be a crossover between these two works. It wouldn't take much to make it happen, either: just the vampires staying around to see the world speed up and slow back down. Saying they remember when the world was cold, when humans come to speak with them.

Fewer humans means far fewer vampires - the ones who've stayed on, through everything, live in a loosely-connected society of their own now, if predator animals like tigers can have what's called society. If what was described in the Le Guin short story "Solitude" can be called society. Which it is. It's just hard for humans to see it. The remaining vampires each have their own individual territories for hunting and protecting - large spaces fiercely guarded and well defined. A settled vampire have to defend their territories from the rare incursion from other vampires looking to oust them and claim it for themselves, and what demons remain that want to harm their humans. Most humans know how to set up protections and defenses the way most humans know how to navigate by the stars at night. But sometimes the vampire helps out in their own way, usually without anyone knowing.

Sometimes another vampire comes by for company. And, like the humans in "Solitude," they'll see each other for a while, and then go off and be alone again and still be happy.

Cold people. Night people. People outside the word dance. People with their own dance.

It's easy for me to imagine a version of Always Coming Home with small references and warnings scattered throughout and a dedicated segment in one of the reference chapters about them, and the proper protocols for dealing with them. What to do when you find a dessicated deer carcass in the woods hung up somewhere for people to notice. How some other places will put out an animal for their vampire, a calf or kid to keep the cow or goat in milk. How to approach them, if you want to talk, and how to set out the proper offerings to see to that. Because they've got stories to share, long stories, because they've lived a very long time. Some of them have walked on the bottom of the Inland Sea - not by weighing themselves down to stay under the water, though a few have done that. No, they walked on the bottom of the Inland Sea back when it was dry. That's how old they are.

The world will never be that cold or that dry again, they'll say.

I can see Spike in this role, following the lessons he got centuries ago in a town that's currently a deep underwater cavern from people barely referenced in the Archives. He found a new place like that town, and held to the memories of those who've gone, and set his claim on the territory. And sometimes people come to him to talk. His hair's back to being brown and curly, and he sometimes comes into town for the festivals and the music. Not to eat or hunt, though; you don't do that in a town. Not here, not with the way the world is now. He knows he's not welcome - nobody welcomes him, nobody invites him, he'd be upset if anyone did because they should know better than that. Sometimes, though, when he talks to the people that are around now, he's glad to be such a long-lived creature. It's given him time to see the world change.

A Short List of Possible Ways to Continue Incorporating Judaism into the Buffyverse

Anything involving King Solomon, right there. "Solomon's Compendium" of assorted demons, outstanding in its field, still the go-to source for a number of species and creatures. Maybe a codex, or some jewelry - definitely have Willow and Wesley reference him at least a few times, whether as a scholarly source or something read about in Sunday school fairy tales. Maybe both.

Giles saying a language needs to be read right to left, Willow smiles, "And Katie said Hebrew school was only good for a Bat Mitzvah." And then she uses that education fairly regularly, correctly grasping the pronunciation of some Aramaic chants and commenting that a pronunciation guide is almost identical to the cantillation trope symbols she learned way back when.

Willow mistakenly thinking Tara was Orthodox when they first met, because her cousins in LA are the only other women she knows who wear floor-length skirts in Southern California.

Los Angeles' eruv being the equivalent of "a brick wall across a motorway" to Angel as he's chasing someone down a seemingly unremarkable street and then hitting something he didn't even know was there, then finding himself deeply thankful he wasn't driving at the time. Because the eruv needs to be strictly monitored and maintained, he's not invited inside. He respects that, though it bothers him a little when the negotiator pulls out a card table, sets it right across the line, and pushes over a folding chair.

(Wolfram and Hart get a tiny office inside the eruv's boundaries, keeping all their Angel-related information secure in there. It wouldn't stop a human from breaking and entering, but it's a way to keep the guy from barging in on meetings.)

(Willow explaining why she can't wrap an eruv around Sunnydale, but she can probably make one around the edges of her family's property if Buffy wants to sit on some grass safely at night again.)

Willow lighting the Sabbath candles and then apologizing for the painfully straight language before reciting "Eshet Chayil" to Tara.

Buffy being explicitly described as "a woman of valor."

A golem or two. Because the eruv's big enough someone has to actually go inside at some point, and they weren't expecting a constructed person to be quite so jovial. And having them on Angel would serve as a nice foil to the robots on Buffy.

Spike mentions bargaining with one of Los Angeles' kosher butchers - cow's not as sweet as pig, but mix in some chicken for flavor and it's tasty enough.

Hamsas as protection - keeping Dawn safe from scrying eyes during season five, keeping everyone who wears one safe from curses, a very expensive item ordered through a secondary supplier from the Magic Box who only takes money orders, because she's one of a half-dozen people who know how to make them correctly and she's got to keep the demands down to what she can actually afford to make. Wesley has one in his apartment, and later his offices in Wolfram & Hart. Of the latter, he says he appreciates the illusion of control.

Lorne listening to Jewish chants and prayers on CD, because of course he listens to everything.

Tikkun olam being discussed, in concept and in practice, in reference to what they do and why it has meaning. To force healing upon the world. To fix the holes in the world.

Stars of David as a holy symbol with the same power to repel vampires and other demons as any cross.

Gunn saying he thought English guys weren't usually circumcised.

("Does it bother you? Using a cross?" Gunn asks, some time later, looking down at the little star hanging from a delicate-looking chain.

Wesley shakes his head, shrugs as best he can while laying down. "I tend to think of them as one more weapon." He considers. "And it's easier to make one in an emergency.")