melannen | Crossover backstories

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fannish:crossovers

Crossover backstories

I have written a lot of crossovers, but most of them I just put together for fun for a story. There are certain ones that get stuck for me, and make so much sense, and often make canon make so much more sense, that I 100% believe them to the extent you can assume anytime I'm playing in a world, that crossover is active, even if I never explictly mention it in the story. I've run into a few of them talking with people lately, so I thought I would make a list! (I have probably forgotten some that I'll have to come back and add later. And I've left out ones like "Ms. Frizzle is a Timelord" that everybody knows are true.)

There are no Young Wizards crossovers. Every universe is canonically part of the Young Wizards multiverse (though they may seem more or less so, depending on their own laws and the needs of their inhabitants) so every fic is a Young Wizards fic and none are crossovers.
Not every universe has Highlander immortals, but a lot of them do.
- Mad Max is an immortal whose memory gets super messed up every time he takes a Quickening. (Or, well, maybe more accurately: a Quickening that messes up its winner's memory whenever it gets taken.)
- The Old Guard is a Highlander movie; the people who invented the Game were just barely smart enough not to tell Andromache of Scythia about it.
- People with the Ancient gene are usually pre-Immortals (unless they're already Immortals) Also, the reason you don't mess around with quickenings on "Holy Ground" is that Quickening energy reacts really poorly with even trace amounts of Naquadah. In fact the whole Quickening thing was originally a defense against becoming Goa'uld hosts that was put in place by the last remnant Ancients on Earth during the first Goa'uld invasion, although that's almost entirely forgotten; descendants of Ancient people who left Earth before then don't have it. (This doesn't quite line up with all the lore but the Naquadah-Holy Ground part makes so much sense that I stick with it anyway.)
  - (Also, everyone on the Leverage team has the Ancient gene.)
Tolkien's Middle Earth is the universe from Diane Duane's Wounded Sky. Which makes K't'lk Ungoliant and assorted other powers the shadows of various Enterprise crew. (Someday I'll write the fic where they get a chance to visit.)
A Night in the Lonesome October gives the AU backstory of A Study in Emerald.
Sister Simplice from Les Miserables is the French vampire from They Who Hunt The Night. She is bleached-white with cool waxy skin and no detectable age, but she lived through the Great Plague, so it makes sense she'd go into nursing. (Honestly any time I mention vampires they're probably Hambly-style unless they explicitly aren't because they make so much more sense than any others I've read.)
The Earl of Red Gloria is friends with the Dukes of Denver.
Machineries of Empire and the Locked Tomb take place in the same universe, but quite far apart. Look the magic in Machineries isn't not necromancy-adjacent and a myriad is plenty long enough for a whole society to grow up that doesn't remember Earth.
The M25 is a demonic sigil in every universe where it exists. Not sure this counts as a crossover as opposed to a true fact that happened to be popularized by a book, but a lot of people assume it's a crossover when they notice it. Most bypass ring roads are demonic sigils actually; if they weren't before they were built they are after people have been driving them awhile. (The bit where CDs or cassettes left in a car turned into Best of Queen is also a thing that's just true that only happened to be popularized in a book.)
Good Omens is set in the same universe as Mark Twain's Adam and Eve Family Papers.
Indiana Jones and The X-Files take place in the same universe. They also share the same government storage warehouse. (I haven't seen the Indy movie that has aliens in it but also I don't care.)
San Fransokyo was built by refugees after the end of the Kaiju threat and disbanding of the PPDC. Apparently it's now canonically a post-1906 earthquake alternate history but I prefer my version.
Due South and Dresden Files are set in the same Chicago (it's just that the Due South characters understand the magic better.)
Every mysterious invisible island in Lake Michigan is the same island, connected interdimensionally (I've collected three so far, but I suspect a lot of worlds have them, it's just nobody's found them yet.)
All large libraries and small twisty bookstores are connected via L-space.
If you need a place where the air is sweet and everything's A-OK badly enough, then from any city in all the worlds, I can tell you how to get to Sesame Street.
The Minecraft "multiverse" is actually a very old Dyson swarm (or possibly a cluster of them.) Bedrock is scrith. You can fit about a quadrillion average-sized Minecraft worlds into a 1 AU full-sphere Dyson swarm, or 70000 max-sized ones, more if they're not completely flat. Yes I've done the math¹, if you assume scrith and artifical gravity this explains everything about Minecraft worlds. Of course there are many more than 70,000 Minecraft worlds but most of them are orders of magnitude smaller than the maximum. The respawn mechanic is that player characters are all cloned ancillaries. (I dare someone to either write Tisarwat and friends visiting that version of the Radch or your favorite Minecraft people making it outside the Radch for the first time.)

1.A standard minecraft "world" is a flat disk approximately 400 m thick, with 150m or so of rock, caves, lava and ocean capped by 250m of terrain and sky, bordered by an impassible forcefield at the circumference. The bottom five meters are made of "bedrock", a physics-breaking substance that cannot be moved, destroyed, or altered using any ordinary methods. The radius of the world is somewhere between 19m and 30,000,000m although very few are near either of those extremes - 30,000m is slightly beyond the largest radius in which End Portals generate in standard worlds, which is probably reasonable as an average size for a Minecraft world.

Minecraft worlds have a constant, equal length day/night cycle marked by the sun moving across the sky at a constant speed from east to west at zenith and then rising again in the east. At night the stars move in the same direction as the sun. The minecraft world also has an 8-day lunar cycle in which a moon remains at full opposition from the sun while going through full-waning-new-waxing-full phases, one per day.

"Gravity" acts differently on different substances and not according the rules of the wider universe.

Things we will not worry about:

The structural viability of the Minecraft world. It's made of scrith, it maintains its shape regardless of any ordinary physical forces.
Gravity. "Gravity" on a Minecraft world does not work the same as Earth gravity and we must assume that large-scale gravity is basically negligible and the gravity effects that are observed are due to a technical artificial gravity system we will not be attempting to invent at this time. The artificial gravity system presumably also compensates for centripetal and Coriolis forces and maintaining an atmosphere and so on.
Absolute time. Time on a Minecraft world is hard to gauge; in theory a day-length is 20 minutes, but things happen in that day that are unlikely to be able to happen in only 20 minutes on any known planet, so we're going to assume that while relative times are accurate (eight days per lunar cycle) there may be some unknown time dilation effects relative to our source of information, and so we're not going to worry about that.
The End and the Nether. That's extradimensional necromancy stuff and outside our ambit.

OK. So, with those postulates, I propose:

Minecraft worlds are individual artificial satellites in a Dyson swarm. This by itself describes nearly all remaining characteristics of a Minecraft world, and a nearly complete Dyson swarm at 1 AU could contain approximately one quadrillion individual Minecraft worlds of 30,000m radius, or one trillion at 300,000m radius. (The best estimate is that far fewer than a billion have ever been visited by a player at all.) And you can, of course, have a larger orbit than one AU or more than one shell, and most generated Minecraft worlds are much smaller than 300,000 blocks.
In order to get the day/night cycle, you have to spin the worlds. While there are ways to fudge a sunrise and sunset on a non-rotating world, in order to have the stars also spin you're basically going to have to spin the world (or else have them be projected on some kind of nearby sphere, but at that point you might as well propose they're some kind of computer-simulated virtual world or something silly like that.). Because we've already postulated artificial gravity and scrith, we can probably ignore any other issues that would result from this. As a bonus, spinning a satellite uses gyroscopic forces to increase its orbital stability, which is extremely tricky and important in a Dyson swarm, so it probably makes some sense to add a spin anyway. (does it make sense to have your swarm components be flat disks with biosphere on only one side? shhh we're not asking that question.)
While the stars would be outside the sphere and therefore might be eclipsed by other worldlets, most of the times when that would be possible would be at dawn and dusk (as the habitable surface of the worldlet is facing away from the interior of the sphere during its night) and depending on how the rotations of different worldlets are synced, the nearest ones might be edge-on during that time. (However, for low-tech empirical proof of this theory, carefully looking for eclipsed stars in the band of sky that's at zenith right at dusk and dawn is probably the best method. ETA: having spent a few nights stargazing, atmospheric twinkling gives the effect of frequent eclipsed stars through the whole sky - so without very precise measurements it would be impossible to tell either way.)
The stars don't, as far as my observations go, move at all relative to the sun, which is a problem because the Sun should move through the Zodiacal ring as the worldlet orbits over the course of the year. However, the orbits of worldlets in a Dyson swarm are an extremely complicated math problem that I don't understand at all. One possibility is that they have a millennia+ long year, so in the ten-ish years of observations we have they just haven't moved noticeably yet. That would actually imply that the Dyson swarm is in a very large orbit circling a very bright sun - maybe closer to Kuiper belt range that Earth orbit range - which would greatly increase the spacing possible for a trillion+ worldlets and reduce the chance of observable occultations of stars.
This leaves the question of the moon. For it to remain constantly in opposition to the sun, each Minecraft worldlet needs to have its own moon, which orbits the sun just outside the world's orbit but at the same rotational speed, remaining stationary relative to the line connecting the worldlet and the sun. In theory this would be the L2 point (the James Webb space telescope is in the equivalent point relative to Earth) but, as the L2 point isn't stable anyway, the "moon" is going to need some orbital stabilization. In fact for any Dyson swarm even close to complete, there would need to be quite a bit of active orbital stabilization, so the "moons" may also provide some kind of external stabilization to the main worldlets as well (if they're in some kind of artificial gravitational relationship with their worldlet, they may be closer than L2.) Some Minecraft worlds have noticeably different moons than others - for example, Hermitcraft Season 8 or SMPEarth - so an individual moon in stationary orbit makes sense in those terms as well.
Because the moon does not move relative to the sun and worldlet, the phases must have a different source than the phases of Earth's moon. One is that the moon is a regular solid body that is simply colored half dark and half light and rotates once every eight days relative to the worldlet. There is also a possibility that the moon phases are caused by periodic eclipses of the moon by the worldlet (maybe as part of an orbital correction cycle?) - the annular appearance of the new moon implies this - but it's half-black, half-reflective and rotates in eight days requires much less math to prove plausibility.

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I am now pretty invested in Fraser finding his way from Chicago to Sesame Street (and also I’m not familiar with the Dresden Files but it may be relevant to my interests)

Fraser *definitely* could, and should, find Chicago's Sesame Street. (Ray Vecchio has probably already been but would deny it. Not Sure about Kowalski.)

Dresden Files is a long urban fantasy series based in Chicago that had a really active and good fandom for awhile! I'm not sure I would recommend it, exactly, at this point; it had the trick of a lot of book series that grow fandoms of having a world and characters that were more interesting than the stories the author was capable of writing for them. But if you like urban fantasy it's pretty fun, at least the first dozen or so (which is the point at which I quit.)

And there's a magical hidden island in the middle of Lake Michigan!

Somehow I am now also reminded of the time ellen_fremedon had a Sesame Street x Doctor Who thing brewing - I don't remember how she got there but I'm pretty sure I was the one who called Mr Hooper the Shopkeeper (so, you know, he didn't die; he regenerated).

Also Mary Poppins is obviously (obviously) a Time Lord.

. . . and now I'm thinking about Fraser going to Sesame Street and finding a TARDIS there, and realizing that what Vecchio and Kowalski are is the First Ray and the Second Ray - only I can't decide if that makes his life make more sense or less.

I do occasionally subscribe to the "there is only one Ray, he regenerated" theory, but I like them as two different people too much for it to make this list. (The car is clearly a TARDIS that got a reskin.)

I don't know about Mr. Hooper, but what does belong on this list is that Grouches are a Gallifreyan species (possibly the original symbiote species of TARDISes, given they seem to obligately live in them.) I waver on Mary Poppins because there are also other things she could be, though.

Edited 2023-04-09 00:55 (UTC)

I think Mary Poppins is heavily implied to be an angel. She and Aziraphale would get along well.

Iirc in bookverse she's actually semi canonically some kind of goddess figure? So angel also works probably!

I think I got there via trying to figure out how Oscar got his hands on what is obviously a TARDIS.

It's pretty clear to me that the "space" in Pigs in Space is the Whoniverse.

Oh no, that makes "Aliens of London" *much* worse.

To say nothing of Daleks of Manhattan

Stargate:SG-1 and the Indiana Jones movies are in the same universe. In the 4th Indiana Jones movie, in that warehouse where they keep the ark and other stuff, you can in fact see the big freaking box the stargate was packed away in between the 1940s and the 1990s. The only potential conflict is that the Abrahamic God is real in the IJ universe (and so, possibly, are the Hindu trimarta), and so far "gods" in the Stargate universe are aliens or really advanced aliens. OTOH, I have written fanfic that theorizes that the goa'uld have been usurping the names of real gods who are none too pleased about that.
Dr. who and the Cthulhu Mythos both have the wonderful property of being able to cross-over with almost any other fictional universe.

Ah, see, I deliberately know nothing about the fourth movie. :p

Is the Abrahamic god canonically real though? I feel like the movies don't quite make a call on that.

Dr. Who is a subset of Young Wizards, since the Doctor make a guest appearance in YW and thus falls under that. :P

Not so sure about Cthulhu verse; I guess I don't have a good enough sense of what the boundaries of it are to even make a call on what counts as a crossover with it. (Though certainly if you define it as the set of worlds in which a Necronomicon or one of its kindred books sit in a library's locked stacks, that is very many worlds. And many Massachussettses have a Miskatonic U.)

Well, *something* melted a bunch of Nazis when they opened the Ark of the Covenant, and the Holy Grail did a lot of weird things -- if you don't want to call it the Abrahamic God because something also got very annoyed that Hindu artifacts were also being misued, fair. But something supernatural is very willing to act in the IJ canon, and that's would have to be reconciled if Stargate also happened in the IJ timeline.

There's plenty of supernatural powers and technologies that can appear godlike in Stargate though - I feel like you could probably explain everything that happened in the first three Indy movies via stuff that's happened in Stargate canon without requiring any gods to be more real than the Ancients. Indy leaves more *space* for them to be real but doesn't require it. They're both built from the same "Ancient Astronauts" bones, though I guess it's less obvious with Indy if you haven't read way too many 70s UFO paperbacks, since the theory has changed a bit in feel over time. But SG1 has both an Ark and a Grail and while their powers are a bit different they're not out of range of what the Indy ones do.

I once figured out how to make the universes of "Blake's 7" and "Firefly" intersect - basically, the Federation of Blake's 7 is built up from the people who remained behind on Earth-that-Was (aka "earth") when the colonists from what became the Alliance headed out. The two governmental systems are aware of each other, but there's a very solid agreement between them that there shall be no official contact - on the Federation side, it's very much "we don't need you, you abandoned us"; on the Alliance side, there's the very real fear if it becomes known leaving Earth-That-Was hadn't actually been necessary, there would be widespread revolution (particularly since the Federation now occupies far more territory than the Alliance ever laid claim to). So the two governments stay in contact, but it's very much a "you stay over there, and we'll stay over here, and if we don't interact things will stay peaceful".

Of course, this diplomatic agreement isn't known of (or heeded) by those on the margins, such as the crew of the Liberator or the crew of Serenity, and there's a bit of profit to be made on both sides trading things back and forth to fill gaps here and there.

That's pretty close to how the Machineries and Locked Tomb one on my list works! Honestly, most lost colonies/space empires ones can be crossed over this way pretty trivially, because space is very very big, unless they have canon timeline issues that make it not line up, too many contradictory details about Lost Earth, or extremely incompatible technobabble.

With Firefly I could never quite figure out for myself if it was really supposed to be set in just one really big solar system with a whole lot of settled planets, but if it is, you can slot it into pretty much any space fandom as just one solar system that the main characters had never bothered to visit before.

Oh, and also: if you're wanting to cross practically any Disney movie (and this could potentially extend to the MCU, and thus the Marvel universes; it definitely includes the Star Wars universe) with just about any JRPG continuity, the things to use are Kingdom Hearts (which is Disney meets Final Fantasy[1]) and the Mario fighting games (which are Mario meets every known Japanese major character out there - including both Cloud Strife and Sephiroth from Final Fantasy VII, both of whom show up in Kingdom Hearts).

It's also worth noting the Whoniverse is canonically part of the various Marvel comics universes as is the universe of the Transformers. So yes, you could, theoretically, have your favourite Transformer meeting up with your favourite JRPG character by transporting one or both of them to their location via TARDIS through Kingdom Hearts and Marioverse.

[1] Final Fantasy is full of Star Wars references; therefore the Star Wars universe has a direct "in" to Kingdom Hearts regardless of whether the House of the Mouse agrees or not.

Oh, jeez, once you've started trying to canonically connect up things that were at one point part of mainline Marvel continuity or canonical alternate universes thereof, the red threads just get more and more tangled! Fortunately it doesn't take long to hit the Star Trek:TNG crossover miniseries with the X-Men, and Star Trek:TNG also has a canon YW crossover, so it falls under the YW rule pretty quickly. (Not to say it isn't still fun to try to play 6 degrees the long way!) Honestly, Marvel canon has so much canonically nested inside it that it's one canon I've never been all that interested in more conventional crossovers with!

There are no Young Wizards crossovers. Every universe is canonically part of the Young Wizards multiverse

I'm still in awe of how well you made that work for the Rivers of London universe.

Every mysterious invisible island in Lake Michigan is the same island, connected interdimensionally

And everybody who lives on it is named Reynold except for Helena and Raymond?

Well, that's definitely true of all the lizards that live on it, at least!

This works.

If you consider the Indy movie with the crystal skulls as a fever dream that is not really connected with the series, it works very well and is very funny. I do, however, like Indy on the motorcycle in the library answering a student question by telling them to get out into real life more.

Indy and the crystal skulls fits real well with a Stargate crossover, though.

Does it actually match up well with the Stargate episode with the crystal skulls?

Sadly, it's been so many years since I watched either one that I couldn't say.

also... all of the universes linked by John Munch - for there are many. i don't actively write in most of them, i just find the concept amusing.

i do tend to put the White Collar and Suits worlds together

and there was a trend in the early 2k's for slapping Sentinels everywhere, ala Jim Ellison

Sentinel AUs are fun to play with but I don't think any rise to the level of me thinking they're canon. Except maybe Javert. There was definitely a period where the greater Seacouver-Cascade Twin Cities Metropolitan area was its own thing though!

White Collar and Suits definitely meshed well, and I always kind of thought they were probably also I the same universe as Leverage and Boston Legal, but I never watched enough canon for either one to have real opinions.

(does it make sense to have your swarm components be flat disks with biosphere on only one side? shhh we're not asking that question.)

Not a huge mincraft person but honestly you probably could make an argument that both sides of the disk are biosphere, its just impossible to traverse between them.
Some finagling necessary—worldpairs presumably need simiar modpacks and therefore similar artificial physics systems, but even that can be handwaved with ‘oh we just havent seen the other side of that particular world’

That would be a good theory but you can actually break physics to get through the bedrock layer, if you know the tricks! At which point you fall endlessly into empty space and rapidly die of void, because Minecraft is like that. (That's actually the main reason I decided it was a megastructure, because the most famous Ringworld in SF also has a hole in the scrith you can fall through and die in the void of space. Although it spins for gravity, so the hole is a bit more dramatic than in Minecraft.)

If you have extra healing & technology & you're careful you can actually explore under the world quite a bit, which is also why most of the machinery must be on the moon and not under the world. (The only thing is that there's no stars, sun or moon in the void, but let's just assume the void messes with your distance vision.)

Edited 2023-04-09 15:58 (UTC)

Ooh, headcanon accepted.

Which one? :) Although they are all very valid it's true.

The Old Guard and the Ancient gene were the ones that caught my attention first.

K't'lk is such a great primordial force ♥♥♥♥♥♥♥♥

It just works so well (and the crew are canonically Tolkien geeks in Diane Duane's books - they named a planet Lórien! - so if they were going to sing a world into existence, of course it would be that one!)

I think Netflix’s Daredevil is in the Highlander universe. Matt Murdock is an immortal who had his first death sometime in season one and didn’t notice.

I like that! Although tbh I feel like Matt Murdock is the sort of person who could die, not notice, and get up again, whether he was a Highlander immortal or not.

He has his crazy senses already—probably wouldn’t think too much of sending other immortals. And he spends a LOT of time on holy ground. I could see other immortals running into him and going oh fuck no. Not worth it. That guy fights ninjas.

>>Tolkien's Middle Earth is the universe from Diane Duane's Wounded Sky. Which makes K't'lk Ungoliant and assorted other powers the shadows of various Enterprise crew. (Someday I'll write the fic where they get a chance to visit.)<<

I love this SO MUCH.

>>All large libraries and small twisty bookstores are connected via L-space.<<

Yep. And once you've created a bookspace, then from any other sufficiently powerful bookspace, you can summon your own. So you get to your Afterlife, or Underhill, or Shoreleave Planet, etc. then you don't have to rebuild your library, you can just use the Fetch command and it will do that. Or Fetch a subset, because once you've built up a really big bookmass, it gets to where what you probably want is A) your all-time-favorites and/or B) relevant sections of reference materials for a current issue. "Fetch my office, my thousand favorite titles, and the top hundred in the categories of Dream and Freedom," or whatever. This life, I've got well over 10,000 volumes in house and quite a nice nugget of "jumpstart a civilization" so that'll be very handy to keep.

A large library is definitely a thing of joy!

Have I mentioned how I love your brain?

Sometimes it's good fun!

On Young Wizards not-crossovers:

Mmm. I am reminded of the pair of (brilliant) Yuletide stories by oniongirl in which the issue of fictionality arises as we have characters traveling to and from Gotham City in one 'verse to NYC in the other:

"Do you think they're going to remember?" Kit asked, "You know,
that they were here...I mean, that they were here and found out
that they aren't...aren't..." He trailed off, because it was
difficult to think of Tim or Dinah or any of them as...fictional.

"Tell you what, why don't you test it? Travel to a universe where
we're fictional, and then come back and see what you remember."

On Duane's Wounded Sky:

I would swear on a stack of wizards' manuals that when I first read that book lo these many moons ago, I caught the phrase "further up and further in" somewhere in the climactic sequence, which would arguably make that novel canonically Narnian. That said, I have on more recent attempts at rereading been wholly unable to find that phrase again.

On Mary Poppins:

I ended up using the title for something else, but I had an idea at one point for a story in which Mary was a rogue Watcher in the Buffyverse. (OTOH, I actually wrote the story in which we establish that Mary was governess to Sherlock and Mycroft Holmes back in the day.)

Characters dealing with traveling to fictional universes (to them) are always fun! I bonded to Heinlein's book that goes really deep on the question at a young age (and have written fic about it.)

Further up and further in definitely sounds like it would have belonged in that sequence! I quit Narnia before the Last Battle though, so I wouldn't have caught it.

Mary as a rogue Watcher makes a lot of sense actually!

a lot of great stuff in here, but especially the old guard/Highlander one because yesssss that is so accurate

Yeah I feel like that one's basically just canon! Like, there's some weird extra stuff going on with them, but there are plenty of canon Highlander Immortals who also have weird extra stuff going on; "MacLeod encounters a group of Immortals who have strangely linked Quickenings and don't know about the Game" could absolutely just have been an episode. (Which is why it's tragic there are so few actual HL crossovers written.)

YES. Exactly! It really could just be canon! and really EVERYTHING needs to be a HL crossover. Back in the days when HL was my main fandom, and for years afterwards, I was just like, stick Methos into literally any other canon and you can get away with it just fine, and I want to read ALL of them. Still do want to read all of them tbh!!

Same!!! Actually after writing this entry I actually made progress on the Stargate crossover that led to those headcanons in like, 2008.

Although also there needs to be more non-crossover HL fic still too. I'll take either way! (I say, while never signing up for the exchange, ever.)

oh incredible, I love that the stargate crossover is still in active work even after 15 years, I am truly impressed!

Although also there needs to be more non-crossover HL fic still too. I'll take either way! (I say, while never signing up for the exchange, ever.)

MOOD

Have you read the one that goes Peter Wingfield played a minor character in X-Men 2 -> who could plausibly have been Methos -> Methos would probably find something very familiar about Wolverine and then runs from there?

oh I absolutely have! I have read so many Highlander crossovers :D

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Crossover backstories

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