Incorporating new canon into existing stories

This one is a bit of a touchy subject, an argument that I expect will rage eternally no matter what anyone says on the subject. Naturally I feel the need to add my own penneth worth to the pile.

I've talked about canon before, where I touched briefly on holding too close to canon in a work that is still in production:

Ultimately, canon only becomes rigid after the franchise ends, at which point it is set in stone and cannot change.

[...]

Until the work is complete, it's a bad idea to stick too close to a rigid definition of what is or is not canon. If the franchise itself can be so flexible about canon, then it is ludicrous to hold ourselves to a standard that even those who are paid to produce the work do not hold themselves to.

At the time I also said that a living canon will inevitably contradict your own interpretation of it - you will eventually find a point where your fiction diverges from what's on screen, and that's just fine. However, I didn't address how to deal with it in any great detail beyond treating it like a buffet, and to pick and choose what you want.

Of course one option is to ignore it the new canon entirely, shift over into a parallel universe and just carry on as if it never happened. Sometimes that can work extremely well. Your fic goes on, you get to the end, bask in the plaudits and praise and everything's dandy.

However...

There are times when you might like a particular idea from the new canon - you might think it expands the character in interesting ways, gives them a more solid backstory, or that it's just so cool that you can't leave it out. It might provide some explanation for a particular element of the world.

Or there might be times when you just feel that there's an integrity issue in ignoring a particular piece of canon. You may not like it; you may even despise it, but it fills in a gap, or it explains something, or pulls things together and you know you have to include it to remain true to the character or the setting.

How do you go about it?

First, the simple thing: does the new canon contradict your existing efforts?

No? Great!

Yes? Then you have to consider how much effort is involved in incorporating that canon. Does it require a fundamental rewrite of your story? And, the important part: are you willing to undertake that rewrite?

You can't progress until you've answered that question. Necessity isn't an issue: willingness is what matters. If you're willing to rewrite your entire story to incorporate a fairly minor detail about Steven Magnet's love life or the existence of the Kahlúa in Equestria, great! But if you aren't willing to make that change, then there's a simple solution: don't. Don't change things just because you think you have to. Lebwoski will just have to get his White Russian somewhere else.

If you are willing to make that change, or if you think you can put in the new canon without any detrimental effects, then you have to consider the next step: does the new canon materially advance your story?

This is one of those mushy "might be optional" sort of affairs. On the one hand, little details and ideas that have no actual bearing on the plot are interesting to throw in. They expand the world, fill out the story. They make things more real and rounded, and immerse the reader more completely.

On the other, throwing in extraneous ideas can bog a story down, cluttering up the plot and diverting it into holding patterns as you expend energy and time exploring those ideas without any real benefit to either the reader or the characters. This is why it's always a good idea to have at least one eye on whether this nifty new idea will advance your plot in some way.

Of course by "advance" I don't mean push the characters or the world forward - plot advancement isn't just a linear progression from A to B to C to Z. It can "advance" by filling in some background - expanding your protagonist's motivations, perhaps, or shining a new light on the antagonist's actions. It can even advance by pausing for a moment, creating a momentary eddy to let the characters - and the reader - relax and feel safe for a time before you move on.

See what I mean when I said mushy? Exactly the same thing can be good or bad at this point depending on how you handle it.

The final step, which is largely a repetition of the previous step from a different angle, is simple: does it actually matter? Does the fact that Berry Punch has an unreasonably close relationship with a keg of fruity beer matter to your story about Matilda's secret life as a donkey fifth-columnist working to undermine Equestria's entire system of government?

I've seen so many stories throw in references to things that simply had no relevance to what they were about, just so they could incorporate new canon - stories where the author deliberately went out of their way to throw in a knowing wink to something just because it was canon now, forcing in things that were entirely and utterly irrelevant to everything, just because.

I mean, sure, if you can make it fit...

In the end, as with any other element of writing, that is the sole consideration: Can you make it work? Does it fit?

And if it doesn't, why are you trying to force it in?

Enjoy the buffet, and remember: it's ok to not eat something you don't like.