Create a timeline
As the site's story becomes clear to you, start to create a timeline of key events. Put them in a relative order: this happened, then this, and then this. Vague times are usually fine (centuries ago, decades ago, years ago, last winter, last week, etc.).
If your site is more than a decade or so old, refer to ages of the world (Book II). Try to align your site's timeline with that of the setting.
If you're prepping the site in advance,
then write this timeline down in as much detail as you find useful. It's typically a bullet list of key events, but you can include details like the motives or experiences of actors in the site's story. If you're so inclined, you might even draw maps or illustrations of the place at various points in time to visualize how it has changed.
If you're improvising a site during play,
then keep things high-level. Focus on the details relevant to play. If you're creating a Stone Lord ruin that's been haunted by a ghost for a few decades, then gloss over the ruin's origins and spend more time on the ghost's death and subsequent events.
New questions will arise as you make your timeline—answer them! As you make new connections, reconsider previous decisions. Adjust your timeline accordingly.
When you think you're done, read over the timeline from beginning to end. Look for obvious holes or contradictions. Address them as needed.
I've laid the foundation for my Green Lord tomb; it's time to build up its story. I start by looking for connections.
The Green Lords bred the Fae to create false afterlives for themselves. But when the Fae rebelled, they "gutted tombs." So why is this tomb still intact? (A question for later!)
The tomb is in the Great Wood, so the Forest Folk must have known about it. The area is probably marked with Forest Folk glyphs.
Rhianna and her pa found what looked like a burnt offering left outside this place, which they think the Forest Folk left.
Forest Folk descended from the Green Lord's mortal servants. There's a mummified Green Lord in there. Did they worship it?
Blodwen's player is curious about the Forest Folk; she might be able to learn something about them here.
Sajra is a swyn. The Green Lords made swyn with help from the Things Below, to fight the Fae. The Fae hunt swyn.
Sajra moved in last autumn, and kicked out a Fae named Thornthumb. Thornthumb was a collector himself, so some of his hoard must still be there.
Thornthumb would know all the ins and outs of the tomb. He would have known (and traded with?) the Forest Folk before they left, too
Sajra has turned the crinwin into "fawning servants," but their instinct is "to covet." They're probably jealous of the children's place in Sajra's collection.
From there, I make a list of questions and then start answering them.
Why didn't the Fae gut the tomb during their uprising? The inner vault is guarded by powerful, loyal Fae. The outer tunnels were looted and ransacked, but the vault and Green Lord are secure.
When did Thornthumb move in? A few centuries ago, after he lost his home in the Fae revolt.
What did the Forest Folk think of this place? They treated it as a sacred site, petitioning the Green Lord like an oracle or (fickle, dangerous) god.
What was Thornthumb's relationship with the Forest Folk? Did he act as an intermediary between them and the Green Lord? Or charge them a toll for passing through his home? That second one feels right.
What caused Sajra to come here? Swyn hate each other, but they do breed occasionally. I think Sajra is young and came here to establish its territory? This makes me think that swyn have genetic memory, and hatch with much of their progenitors' knowledge and cunning.
What minions did Sajra bring with it when it arrived? If it's young, probably not many. Some crinwin from elsewhere, but that's it.
What treasures did Thornthumb leave behind? It could be anything. One of the Mindgem's missing parts? Eh, that just feels too convenient. Not sure I need to answer this just yet.
How did Sajra get Thornthumb to leave? (Threats? Violence? Trickery?) It took over his mind and had him gift Sajra the tomb and his hoard. Now he's oathbound to stay away.
Has Sajra met the Green Lord? No, I think it's stymied by the guardian Fae. But it wants access to the vault—it thinks it can overthrow the Green Lord and claim its treasure and servants.
Where do the crinwin actually live? I think Sajra loathes the crinwin. It lets the most-trusted ones (who came here with it) nest in the tomb, but not in its quarters. The new crinwin nest outside.
What's the crinwin's relationship to the children? Crinwin are jealous but also curious, creepily mimicking the kids' words and songs. The kids are scared of the crinwin, but mostly kept in a stupor.
What do the crinwin think of Sajra? The "trusted" ones basically worship it, and lord over the new ones. They mimic Sajra's voice and collect its discarded "treasure." The new crinwin fawn over it and desperately want to please it.
What do they all eat? Crinwin forage small game, grubs, roots, and (gross) food for the kids. But Sajra goes out periodically to hunt for itself. I can't see it living on the crinwin's meager fare.
As I put the site's timeline together, I realize that the Fae rebellion happened in the Age of the Makers, millennia ago, which means that Thornthumb was there a loooong time. I bet he used his sway over plants and trees to help keep the place hidden.
When I'm done, the timeline looks like this: