Bring one detail back
The GM is holding a map, a villain, six side quests, and a note that says “the innkeeper is lying” with no memory of why, so small things fall through. The name of the kid the party promised to find, the debt somebody swore to settle, the door everyone agreed to come back to and then left alone for eight sessions.
Between sessions, anyone at the table writes down one detail from the last game they’d like to see again. It’s one person, place, promise, or odd unanswered question, with nothing for the GM to prepare. At the start of the next session, before anybody rolls initiative, they bring it up.
“Hey, weren’t we going to check on that kid?”
That’s a personal quest the table found for itself. The rest of the table remembers it too, and it works just as well for whoever missed a few sessions, since one thread they care about is enough to pull on when they’re back.
When a player hands the GM a callback the GM had forgotten entirely, the GM can pick it up and run with it as if it was planned all along. It was theirs to begin with, and it’s good for a table to see a world that isn’t perfectly assembled in a binder somewhere.
