From the same school of thought as, "Hey GM, which book did I just randomly pull from the shelf of the wizards' library?" No plot hooks here, just flavor additions.
Found, normally, deep in the swamp, the Friar's Weed's poison is something to be watched for.
When night falls, we find peace in the knowledge that daytime will return soon, and vice versa. But what if the world was split: daytime and night are two different, coexistent worlds, each with it's own laws and rules. At dawn and sunset, our soul switches to inhabit our other being, our 'twin'.