In my Pairs Webcomicking article, I covered teams working on webcomics, and it's my opinion that they usually don't work out very well in the long term. Which doesn't mean partnerships on a short term can't work, the can. In the form of the crossover.
What is a crossover? It's when two comic artists temporarily combine their comics to make a single story arc. How well a crossover works depends a lot on planning and on the comics in question.
Crossovers have been around for decades. Yes, decades, because newspapers have been doing them long before webcomics came onto the scene. Those, though, were often more like extended cameos than what is now thought of as a full blown crossover. It helps that most newspaper comics are fairly static in nature anyway. TV shows, cartoons and comic books have done them as well, so it's no surprise that webcomics should play the role as well.
I suppose it should be no surprise that most crossovers actually stink. Yes, they're generally terrible, and this is because its an attempt to meld two universe that probably have very little to do with each other. The other failure is that the story is often unimportant to both universes in question. This applies to ALL forms of crossovers, not just comics.
At least most TV shows and the ilk have an excuse: Their crossovers are dictated to them, often from an editor or executive thinking it'll bring in more viewers or readers. Webcomics have no such excuse, the creators are the ones that seek out the crossover, and as such when a crossover fails, they suffer the blame.
A successful crossover has to do many things to work. First, it has to be plausable. Simply throwing the characters together in any old way will not work, there has to be a good reason they're all in the same place at the same time. Often this actually means setting up the crossover well in advance and drawing them to the same point, or establishing the universes in such a way that a crossover is not only possible, but likely at some point anyway. Parallel Dementia and Emergency Exit did a crossover together, and their universes, which involve inter-dimensional travel, provided this as an excellent means to draw the characters together.
Next, the character interaction must be believable. Typical encounters between groups of "hero" characters usually involves them fighting, then turning against a common enemy, etc, which is boring and cliched. But that's not the real problem, the problem is that artists are drawing each other characters and probably writing dialog for each other. Some attention must be paid to the script to make sure the characters stay in character.
Which brings us to plot, which has to be meaningful for both parties. Either it pushes each story in a new, interesting direction, or it helps develop the characters in ways that would not be possible in the regular comic. Again, a lot of this requires pre-planning, and most crossovers don't do that.
Finally staying "on model" so people can identify the characters should be a goal of both artists. It's far too easy to slip into your own style and lose the defining characteristics of a given character or plot element.
So you'll note I only make mention of one crossover in this piece, and the reason is remembering crossovers is something I don't go out of my way to do. They're often brief and really DON'T have any meaning for their respective comics in the long term. Parallel Dementia and Emergency Exit (that latter of which I haven't reviewed yet) is just the most recent crossover, and one of the better done ones. The only other one I can recall is from my review of College Roomies from Hell and it's crossover with Fans! which I declared the best I'd ever read. I don't read either of these comics now, so that statement should be taken with a grain of salt and about 6 years.
Thankfully, crossovers very rarely have deadly consequences for a comic, and often they can draw people to reading the opposite side of a crossover. I wouldn't have read Fans! if it wasn't for the CRfH crossover, and I do plan to do Emergency Exit in the future, something I likely wouldn't have done normally. It's one of the many options webcomic artists have to expand their base and hook more readers.
Well, enough of that. Hopefully I'll get a reworking of my failed article form last week for next week. Until then kiddies.