Multiple someones, actually, over email.
I think I’m only to address this once, and then point to this blog post thereafter. This subject, naturally, triggers me, because answering it requires me to comb through what triggers me, the relationship of the triggers to each other, and synthesize all that into analysis.
The media and much of fiction portray something really wrong about triggers: the ideas that triggers are concrete, discrete, reliable, few, consistent over multiple individuals, and unchanging.
First, addressing “concrete” triggers: some triggers are more clear-cut than others. Gunshots, vehicles backfiring, fireworks, etc., are all concrete: you definitely know when they’ve happened. So too are sirens, music—indeed, anything sensual, from sight to hearing to smell, that’s closely tied to the trauma. However, the majority of “triggers” are not concrete—emotions are ultimately the base of any trigger, and emotional state is a complex thing involving many factors, much of it personal.
Second, “discrete” triggers: again, the idea that a trigger is a split-second kind of thing, determined by some event, item, or person that serves as a switch. No, triggers can be much more drawn-out than that; again, this is due to the fact that emotional state is complex and nuanced. A lot of subtle things can build up, slowly altering your emotional state, and thus what actually triggered you is nothing you can definitively point at.
Concrete/discrete versus non-concrete/continuous is shown very deftly in The West Wing‘s “Nöel” episode, where Josh’s triggers fall into both categories: music, and the more complicated, less well-defined identification with the pilot who committed suicide, respectively. I strongly suggest watching this episode, even if you don’t feel like reading anything else covered by the PTSD in Fiction series on Tor.com. Here is the Amazon Video-on-Demand link to “Nöel”; you can watch the episode online for $1.99 (one-time payment).
Third, triggers aren’t always reliable. Some very strong triggers can be quite reliable even outside of context—again, how “strong” a trigger is highly depends on the trauma and the individual’s psychology—but more subtle triggers often have a lesser rate of “success.” And since most triggers are subtle in nature, whether they actually manifest strongly depends on environment and context. And the reliability of a trigger may not always make “sense.”
A personal example: I read some of the Terry Pratchett books and part of the Harry Potter series during my long tenure of abuse as a way to temporarily escape it. You think they’d be a trigger for me now, but they aren’t, not even the same books I read during the abuse. However, the various hand crafts that I also used as a mental escape back then do trigger me now. Why is this so? Only the gods know why.
Fourth, triggers aren’t “few.” The most subtle and numerous ones you may never be able to pick out, because that would be like trying to pick out sub-atomic particles: outside of some really destructive smashing with atomic colliders and much analysis later, you aren’t going to find them. Concrete, discrete triggers are indeed few; but they are far outnumbered by their subtler brethren.
Fifth, there is no universal lexicon for triggers. “What can be a trigger?” Anything can be a trigger. It’s never the case that everything, or even close to everything, is a trigger for a person; but just that anything you can think of can be a trigger. Triggers can be broadly generic; triggers can be incredibly specific; and everything between. Triggers can be concrete, or they may be very diffuse; triggers can come from shopping for pet goldfish or simply brushing up against hundreds of holiday-stressed people. Like individual psychology, and like dreams, triggers are affected by culture, the individual experience, and the individual themselves.
Sixth, triggers aren’t unchanging over the course of an individual. Some triggers may fade away; and new triggers for the original trauma can be created, even if you never directly experience the trauma again. It’s the worst part about triggers: they’re easy to add to by accident. Triggers are, after all, just associations, and all you need to do is to start associating new stimuli with the old feelings. For instance, carrying on any single type of distraction for too long can lead to your brain subconsciously associating the distraction with the trauma. And voila: what you used to do as a distraction becomes instead another trigger.
It’s things like that which make PTSD the… fun… that it is.
In summary: if you’re going to write about characters with psychological disorders, you have to dive deep into their own psychology. Hard work, but you needed to do this when you planned to write character-driven fiction anyways, so….