Hmm! Triggers: clothing is always a good one! But more than triggers, situations and methods are more interesting to me: having to take on a new role (join Santa's reindeer, fill a spot on the football team), having to hide changes, the inconvenience of new body shapes. TF by massage is a nice idea: tactility is great, it's a means of relaxation and self-fulfillment, and it's of necessity social.

I have written a couple TF stories! What's funny is that, while the process of TF is fun to contemplate, nearly every time I write a story that features TF the actual process thereof ends up sidelined. shrug Here are the ones I've written, though:

Secret: https://www.deviantart.com/toledo-the-horse/art/Secret-288106705
Fuzzy Memory: https://www.deviantart.com/toledo-the-horse/art/Fuzzy-Memory-367149806