The Dreamlands are, simultaneously, both the easiest of the otherworlds to get into and one of the hardest.
Heaven is presumably harder to reach, but people tend not to come back, so you don’t get many firsthand reports. Hell, of course, is available at any crossroads or to anyone with a black goat and enthusiasm, and to get into the Dark all that you need to do is be extremely unlucky when you turn out the lights.
Faerie’s borders are rather porous, what with the fairy rings and the mounds and many of the borders stutter back and forth at twilight. Getting out again is the hard bit. Fairies themselves can pass back and forth with ease, but while there are rumored to be openings to the Dreamlands inside the borders of Faerie, the fairies don’t use them much. Fairies are vain, self-centered and above all controlling. Being in situations where they don’t have the upper hand itches at their skin like sandpaper and iron filings. They do not dream themselves, and prefer to be elegant, cool and amused at the bumblings of humans. The mysteries of Dreamland are too much larger, the beauties too strange and shocking, and no fairy anywhere has ever liked to be shown up by their surroundings.
So there is a very small Seelie-Court-in-Exile inside the Dreamlands, but they almost never go home again.
There are also demons in the Dreamlands, who have grown tired of Hell (this is less common than you think.) They are soft-spoken and polite here, and uninterested in souls. They are uglier than fairies, and make better coffee. If one offers to travel with you, accept.
The easiest way to get into the Dreamlands is the usual one that every dreamer knows–to curl up in bed and fall asleep. And dream.
This doesn’t always work. Actually this very rarely works. Not all dreams grant one access to the Dreamlands. Very few of them do. Sleep is a vast ocean, through which dreamers swim alone, and only a few ever wash up on the shores of the Dreamlands. (There are predators in that ocean, but they are fortunately few. Parasites are rather more common. The thing that follows you, and you fight it off and drop rocks on it and hit it with trains and it just won’t die? That’s a fairly common parasite of dreams, rather like a remora. You can kill them permanently with wormwood and salt, or absinthe if you’ve got it. They’re harmless enough, and hardly ever follow anyone back to the waking world.)
Most dreams are only what they appear to be–absurdly intricate mixes of experience and memory, manifestations of anxiety, bits of racial memory. The one where you’re late for class and probably naked? No one needs to go to the Dreamlands for that. The inhabitants are not that interested in seeing humans walk around naked anyway, so it works out better for everybody if you dream that alone in the unlit sea. And some dreams cross all boundaries–practically everyone has the nightmare where their teeth fall out, even species that have only the vaguest anatomical analog to teeth. (Birds dream of their feathers falling out, but it doesn’t seem to be related.) But it doesn’t happen in the Dreamlands.
But all oceans have shores, and on the shores of this ocean lies a place much more real than sleep. And now and then a dreamer stumbles from the shallows of Sleep and up the wet sands (priests and poets leave no footprints, no one knows why) and into the great grim bulk of dreaming.
Time flows strangely here. So does space. There are places that are always the same, and places that are never the same twice. There are places that human dreamers are drawn to, and places they hardly ever reach. There are cities that are almost (not quite) like cities in the waking world, and landscapes that are almost identical. There is a stretch of desert, a saguaro forest, that is the same, stone by stone, as a place in the Sonoran, and as that stretch is eaten away by developers, the edges of the dream desert cease and become something far more unsettling.
Go up the sands into the city, the one easiest to find. It looks a little like Venice, a little like London, with bits of Kyoto juxtaposed in unsettling ways. There is a stretch of road that is definitely from Shanghai, except that the signs are written in Proto-Indo-European, which you speak fluently now, although you cannot remember it upon waking. The gutters run with rainwater–it has only just stopped raining, it has always only just stopped raining– and the water swirls over stones and old take-out cartons and the backs of bullfrogs.
These are large frogs. They eat mice. The local rats have a truce with them, more or less.
Go south down this street. Step over the puddle at the crossing and the suspicious-eyed frogs. Do not wait for the light. The light has never changed. Birds are nesting in it, a bastardized hybrid of house sparrows and firebirds. They do not immolate, but give off smoke. You can light your cigarettes with them, if you can catch one.
Avoid the alley to your right. It leads to a building with a room full of cages, where the animals inside are starving and have always been starving and it is always your fault. (That dream is real. Did you think it was just yours? There is another room in it, much harder to find, also full of cages. There are frogs in it as well, tiny tree frogs, green as bottle glass. They are breeding. You have not failed them.) The animals are not separable from the cages. They are made of the same stuff as the bars. You will not learn who owns this building. The address on the envelopes lead to a street corner with a statue of the Laughing Buddha. The bills are always paid on time.
Are you still dreaming? Good. Go down the street. It leads a long and winding way. Turn left at the shrine full of coins and bottle caps. Take ten steps, turn back. Follow the street again. It will lead out into the desert now, and the wind that touches you will taste like juniper.
What happens after that is up to you.