Writing in the Multiverse

Recently I've been working on a requested revision of a picture book for my agent. It's a quite a bit different than the original, which is not uncommon for picture book revisions. Often a revision is a complete rewrite, taking the same concept down to a blank page and beginning anew. Other times, it's more like a variation on the motif -- new elements added, others deleted, to stay at that elusive 600 word mark within the framework. Sometimes at the end, only a handful of the original words remain.

But this version is a split from my original story -- an alternative, not replacing my previous one, but existing alongside it. Which is the real version? They both are. It feels like I'm writing in a multiverse -- each story is an equally true, existing at the same time. 

I have a friend who rewrote a fantasy into a realistic contemporary into a ghost story. Same character, same motivation, but that single character lives in a different instance of the multiverse where her story plays out in different ways, where magic is real or not real or operates under different rules.

Writing in a multiverse has its challenges. When the versions diverge,  commas corrected or sentences tightened in one version remain in the others. It's frustrating to come across an error you remember fixing, only to realize you were working in another universe when you fixed it.  

Rewriting a book in another direction can be an interesting exercise, whether the revision is requested by an editor or agent, or the writer is trying to make a well-loved story more saleable. Or maybe he's just wondering what would happen if some condition in the story changed -- what if the character chose a different option from a "choose your own adventure" map.

So when you have two or five versions of the same multiverse, which is the true one? For me, it will be the one that gets published. But until then, they are equally true.

Do you have more than one version of a story with a major change or different set of rules? Do you keep separate versions of any novels or does the new version always overwrite the other? Have you ever a sold a version of the story that you didn't feel was your "A" version -- that another iteration was better or truer?