The 'spirit' I've come to understand isn't about rules at all. It’s about a collective permission slip. The raw material is someone else's, but the intent is purely ours—to fix an ending that felt wrong, to explore a background character shoved to the sidelines, to push two people together who never got their due. That impulse to grab a story and say, 'Hey, hold on, I have an idea...' is the whole engine.
It shapes writing by ripping out the usual commercial guardrails. You can write a 200k slow-burn romance between the villain and the hero's horse if you want, because the audience is people who clicked on that tag looking for exactly that weird, wonderful thing. You're not writing for a publisher's market analysis; you're writing for the person in the comments who says 'I’ve been thinking about this dynamic for YEARS, thank you.' That immediate, visceral feedback loop—kudos, comments, speculating with readers chapter-by-chapter—turns writing from a solitary act into a community conversation, and that conversation is the spirit made tangible.