Worldbuilding: Crossovers and Power Levels

There’s a few things a writer has to pull off, IMHO, for a crossover to really work. First, you need an explanation as to why one group of characters suddenly shows up in another group’s setting, or you need an explanation why they were both in the same world all along. Bunnies will usually provide this with some mangling of reality. Second, you need to match tone. For example, I would never try to mix Cat Planet Cuties (the universe is friendly and wants to play!) with Tokyo Ghoul (cannibalism, ’nuff said).

Third and fourth, though – those are tricky. And pretty much interrelated. Third being “thou shalt not stomp on a character’s main schtick”, and fourth being “power levels must match, or this is a Curbstomp, not a fun romp”.

Rule 3 there means that if one of the characters you’re playing with is canonically the best hacker in the fictional ‘verse, then he’s the best hacker. (Unless your whole point is Battle of the Hackers. And I mean a real, evenly-matched, who knows who will win battle.) If someone’s Paper-Thin Disguise works on the characters of one ‘verse, then by golly it works on the characters of the other. If a horrifying monster – say, the man-eating shapechanging Parasytes, for just one example – terrifies everyone in Universe A, then it should utterly freak out those of Universe B who’ve just run into it for the Very First Time Ever.

Or, to boil it down, the crossover ‘verse must be internally consistent. Or at least a valid approximation thereof.

However, adhering to rule 3 can make rule 4 a bit tricky to pull off. There are only so many roles in your adventuring party! So… how to make it so crossover characters can both be key to solving your story’s problem, without anyone stomping on someone else’s toes?

For that, we can fall back on a nifty GURPS trick: base characters on point totals, rather than straight-up stats.

Power levels aren’t just, who can punch through a mountain. (Though that helps.) They can involve a lot of categories. Some I tossed with Kryal a while back include:

1) Experience and training. (Hello Batman.)

2) Organizational support.  (See Stargate Command, or Gentleman Johnny Marcone’s mob.)

3) Mental resilience/grit. (Batman, Samuel Vimes, Shinichi Izumi in Parasyte who reaches new levels of Tranquil Terror.)

4) Knowledge of the enemy. (Ripley in Aliens.)

5) Damage output. (Punching through mountains goes here.)

6) Damage absorption. (Not breaking your hand on the mountain, here.)

7) Unusual background. Some aspect of the character that is either highly unusual or utterly unique to that character in that setting. AKA “You have a crazy backstory as a Phlebotinum Survivor or Adopted By Mountain Ninja Cult that justifies your Crazy Awesome skills.” See Cloud Strife, Harry Dresden, Harry Potter, Edward Elric (clap-alchemy), Blue Exorcist’s Rin as the Son of Satan, Aladdin as the Fourth Magi, and Ichigo Kurosaki as a living shinigami.

Note, most Main Characters should probably have a smidge of 7, or they wouldn’t be adventuring types to begin with.

But that gives you 6 categories to work with where the two groups of characters don’t have to be exactly matched. Maybe one group has great supernatural powers; but do they have a powerful government or Secret Organization that can make sure there’s a hideout, weapons, or help when they need it? If group 2 has that, maybe they don’t need Awesome Magical Powers to be a serious threat to the Monster of the Week.

…Which brings us to rule 5: A serious problem for one universe has to be a serious problem for the other.

This is in part a power-balance thing, in part a “don’t step on people’s schtick/awesome in deciding to be a hero in the first place.” After all, if guys from universe A can simply “set phasers on stun” and take down the Ultimate Villain from universe B, you have a suspension of disbelief problem. As in, “why didn’t somebody do this a long time ago?”

Not to mention you’ve just trashed every heroic act and struggle the heroes from B have accomplished, fighting the good fight against evil. Bad writer. Bad. No biscuit.

…Anyway. Just a few thoughts on what I think Makes Crosses Work. 🙂



23 thoughts on “Worldbuilding: Crossovers and Power Levels

  1. The comparative power level between ‘verses is the problem I have with a lot of crossovers. Particularly crossovers between works that take place on Earth and works that are happening someplace other then earth.

    I think the worst offenders I see are crossovers with shonen series like Naruto and One Piece, as the *weak* skill levels in those series is so far above whats considered *weak* in a lot of Earth based works (clones! sailing skills!). Bleach doesn’t seem to have this problem as much as most of the skills in it (before the whole Fullbringer arc anyway) only really work/make sense in the various after-lifes when people aren’t in physical bodies in the first place. So it fits nicely into how Marvel has various dimensions/planes of existence that don’t interact all that much unless there’s an emergency.

    The same thing goes for settings like classic D&D or The Elder Scrolls where power levels are all over the place and can range from fighting people with swords to full on Reality Warping powers.


  2. While in general I’d agree with this, some of the most interesting crossover fics I’ve seen have completely broken your rule about stuff balancing between settings. Of course, all of those have also made a clear distinction between the settings, too. It’s not just “both settings are really part of the same greater setting”, instead it has to be “this one setting is an OCP.” Tho that sort also needs to be much more careful with the other stuff you mentioned here, as well as the equivalent set of balances involving the circumstances/plot instead of the characters themselves. It is definitely more difficult to write a story like this, from what I’ve seen of them.


    1. The best stories of this sort I’ve seen are ones where A and B are BOTH OCP to the other – for example A’s problem is hella difficult for A, but super easy for B, but at the same time B’s problem kicks B’s butt all over the map and back but A knows exactly what to do with THAT – it’s just getting the solutions to each other, and then dealing with what happens when the problems of A and B join together into the supermonster.


  3. I think that there is also a difference between a setting requiring a certain power level and allowing one. For instance, Marvel can range from gritty street level to phenomenal cosmic power, which can let you play a lot more, versus something like original Buffy.


  4. I’d agree with those rules.

    Too much favoring of one universe over another often feels like an excuse to show much more awesome universe A or its heroes is over universe B and it heroes. Which unless that is the point can be rather dull. Some of them don’t do that exactly but you can tell which of the characters or set pieces the author really likes.

    There is a lot of temptation to Curbstomp – especially the characters you really don’t like – and again, sometimes that one kind of one-sided battle can be very entertaining.

    Of course thinking about crossover logistics has got the bunnies musing. Like how one might work out things up if Rurouni Kenshin and Harry Potter existed in the same universe . . . adding youkai and hanyou to RK is always fun . . . and okay, maybe the bunnies just what to see just well Death Eaters would fair against the likes of the Demon of Kyoto, a Wolf of Mibu, and a certain Okashira (and possibly a certain mountain hermit). Not very well, considering their habit of underestimating certain people, especially “half-breeds.” And some ideas about how a wolf youkai or hanyou might be able to help a werewolf . . .

    Also I have noticed more than few fics that the author is calling a crossover that is more like a fusion. Like the main characters from both Universe A and B are involved in the plot but it is clearly operating entirely within the setting, rules, etc of either Universe A or B.

    Now that kind of fic can be very interesting and fun. Like what if SG-1 were witches and wizards of the Harry Potter universe with the Stargate Command stuff being a US Department of Mysteries thing?


      1. *grins*

        You have to admit that magic, actual magic, as an explanation for certain things makes more sense than their attempts to science it.

        And Science would appreciate the break from having its arm twisted behind its back until it cries and gives up its money lunch.


  5. Where do stories that my teen calls ‘derailing’ fit in? This is where crossover characters land in, say Potterverse early on, pre-harry-hogwarts, and for whatever reason get involved, take out horcruxes/voldemort, and leave. (Even the Wizards Must Pay is the only sort of example coming to mind, but there are probably others.) There’s another type, too, that Metisket just put out an example of today: Xover characters drop into new world, the problem is what happened, and getting them back. no impact on main plot, power levels not really an issue. Metisket just did that very nicely with FMA and Harry Dresden.

    Or what said teen is planning, which is a massive takeover of the wizarding world by competent x-over people over a time span of 50 or so years, incidentally dealing with Voldie along the way, but the real problem is … well, everything in the culture, as wittily summed up in Collateral Damage. (I honor the ambition, and hope Teen pulls it off.) (Potterverse, where the worldbuilding is so sloppy you can do practically ANYTHING with it.)

    In CD the writer handicapped the overpowered crossover characters, so Hogwarts was still standing by the end (if not by much), by giving Ichigo a problem that couldn’t be solved by that sort of extreme violence. The other uber competents had the same problem the Potter people did – finding the horcruxes. So I guess this is an example of consistency in the xover-verse plus knowledge in the characters, and handicaps are handicaps. (horcruxes are hard to find even if you’re a death god.)

    Minor rant because I feel like it: One thing I don’t see the point of, but there are a lot of them out there, are the canon run through with extra character. If nothing is going to change due to the crossover character’s presence, just what is the point?

    Your Artemis Fowl/Avengers thing was really good, without messing with any of the story lines as far as I know them. Crossovers can do that too, if the writer is good enough.

    One reason I enjoy your stuff is it is balanced, and you manage to make it comprehensible even when I have no clue about the original. Although I may now dig into the Magi.


    1. Huh. “Derailing”… hmm. On the one hand, I like some of those because Gah Plot Induced Stupidity, Set It On Fire.

      OTOH… that’s no playing fair with the canon ‘verse. Or to put in terms a chef once used, “The mark of a great chef is not what you can do with a steak. No one should be considered great because they can cook a great piece of meat! The mark of a great chef should be what he can do with the most gristly, toughest piece of meat there is.”


  6. I have had problems with a crossover I’ve been thinking about.Final Fantasy1-X2/ Worm(altaverse) [SO4 Charms and assorted other things!]


    1. grim: adjective, forbidding or uninviting.

      Grimm: Either the fantasy TV series or the Brothers Grimm of fairytale-collecting fame.

      I think you mean the first one? Because otherwise there’s an in-canon crossover already, ow.


  7. And this? All of the above? Is why I have to distract my bunnies with shiney because they keep wanting to chase a Voltron: Legendary Defenders / post GaoGaiGar FINAL fic.

    FINAL’s ending left a wormhole creating castle spaceship sized hole that Voltron could fit real easy like. However, FINAL also introduced Genesic GaoGaiGar who canonically //obliterates planets// by looking at them funny*. That much power would break Voltron’s continuity. Or make GGG looks really, really pathetic in comparison to the Paladins for a good long while. Which breaks the rules of a good crossover. Again.

    Still. All those lions makes it so tempting. So very, very tempting….

    *Okay, not quite. But FINAL blew up a solar system close to a decade before Gurren Lagan made it infamous! Said solar system explosion would also be why GGG would look pathetic next to the Paladins for a while: They did not get out of that fight unscathed.


    1. SRW W already did Golion and GaoGaiGar. I think it may have been one of the SRW games- that did a fix to FINAL’s ending.


  8. Some of my favorite crossovers keep one group OP, but introduce them to a world with complex problems that aren’t just solved by a straight-up power competition. This generally works best when there’s a time constraint so the OP people have to prioritize and there’s the chance of failure just because they might commit to an action at the wrong time and be unable to deal with something that comes up at the same time. This hasn’t gone entirely in that direction, but the fanfiction Thaumaturgic Awakening ( does this type of thing with a complex, difficult to solve problem.


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