The River and the River

Near the Amazonian city of Manaus there is a place where the Amazon proper (the upper section of which in Brazil is called the Rio Solimões) meets the Rio Negro, which flows in to meet it from Colombia. The Amazon is cooler, faster, and carries sediment from the Andes; the Rio Negro is slower, warmer, and full of decaying plant life. For a period the two run alongside each other in contrast, until they gradually integrate:

This is one of those places in the world which screams 'Make me into a setting for an RPG, you fool! Do it at once!', and the setting indeed almost writes itself. Clearly, the two rivers bring with them two very different sets of fantasy furniture, and where they meet there is a great city which incorporates both. Perhaps, indeed, that city is even a kind of neutral zone where two otherwise hostile ways of life can live alongside one another in something approaching harmony. And naturally, there's a megadungeon underneath.

The Dark River is organic, magical, sensual, amoral, ritual-based, and fecund. But it also partly originates in, and incorporates, death and decay; many of its inhabitants are undead. It is powerful in the sense in which a jungle is full of green vibrancy and dangerous life. 

The Light River is inorganic, holy, rational, moralistic, honour-based, and productive. It ultimately comes from the mountains; it is imbued with elemental energy. It is rich in the sense that mountains bring forth the wealth that is buried beneath the earth. 

It is too easy to say that the Dark River is feminine and the Light River masculine, or that the Dark River is yin and the Light River is yang, or that the Dark River is right-hemisphere and the Light River is left-hemisphere. But it is hard to get away entirely from those binaries and they exist for a reason and are enjoyable to problematise and poke and prod at. I would want the setting to hint at and echo them without trading on the distinction too obviously. The contrast between jungle energy and mountain energy seems more 'right' to me somehow. 

The peoples who dwell along the two rivers are mutually antagonistic for all manner of reasons, but the city imposes order on them. It is a city which I think ought indeed to be ruled by a race of giant warrior-women, the Amazons of legend, who forge the two river-worlds into an uneasy but cohesive polity. Presuambly, that city is situated on a river island around which they both flow. Maybe it is even situated on a river island that lies in the middle of a delta: maybe these two rivers come together only at the very point at which they meet the ocean:

What lies beneath? What do PCs who come to the River and the River explore? The science fantasy impulse suggests that buried beneath the island is an alien space vessel; the straight fantasy impulse suggests the ruins of a lost civilization; the horror impulse suggests the corpse of a dead river god, filled with demonic entities. The PCs venture down to bring forth what treasures lie buried there.

These are the thoughts which occur to me sitting in my office idling away when I ought to be working. What are yours?