Rule of Threes and the Rilmani

I think you underestimate the Rilmani. As you said, they're extremely secretive, and due to their Shapechange abilities, they can be anywhere, at any time, and no one would be any the wiser. I think they are just as big of an influence on Planar Politics as the Yugoloths, and perhaps bigger, as they don't limit themselves to evil quite as much. They are definitely not in any danger of being replaced though. If anyone is in danger of that, its the Modrons.

I'm not saying I personally would. I like the Modrons, just like any good (non-chaotic) planewalker. I'm just saying that they are in danger of losing Mechanus to the ants if current trends continue. You'll notice that in third edition, Modrons are relegated to a web enhancement that maybe a tenth of all players will see, where as Formians are in the Monster Manual 1. That puts them up there with all the other exemplars save Rilmani, who don't reappear until the Fiend Folio. But that is another matter, for the Keepers of Balance move in mysterious ways.

Rilmani are the true puppet masters of the planes. Everyone thinks it's the 'loths, but it's not, they just crave the attention and pretend to be behind it all - they're not. It's the rilmani, I tell ya. Rilmani!

They say they "maintain the balance". What's that mean? It means they mould the multiverse to their whims, and when they get it close enough, they call it "balanced". They built the Spire to chain the planes and planars - when you walk away into the Hitnerlands, doesn't the Spire draw you back? They made up the handy little phrases like "unity-of-rings", "rule-of-threes", and "center-of-all" and propagate them cunningly, harvesting the belieef of the common berk for their own goals.

They keep us chained, the miserable lot. They don't want us to see the big picture. But we'll be through with them soon enough. The Spire is falling down, my fair Lady. See >here<

Hmmm, and then theres another idea, what if the Hinterlands in a way are *feeding* the outlands more territory as they loose it?

They do that anyway, though; the terrain becomes wilder and more mercurial as a traveler approaches Xaos, major features moving around ever quicker and more arbitrarily even than what is usual in the Outlands; it is more rigid and structured the closer things get to Automata, until the terrain around Automata, Rigus, and Fortitude forms natural grids; things are more desolate, gloomy, and hostile near Hopeless; more twisted and macabre near Plague-Mort; more fertile, forested and lush near Faunel and Sylvania; cleaner, crisper, and brighter near Excelsior; more peaceful, soothing, lulling, and languid near Ecstasy.

Only near the Spire - and perhaps far into the Hinterlands - does the Land have a shape of its own. And perhaps the Spirelands aren't the Outlands' "true" form either, but only yet another contamination, this time by the Balance instead of by one of the planes of the Ring. Though the gate-towns are crucial nexi of travel between the realms, "spillage" between worlds is an integral part of the plane. It probably is in the Great Ring, too; Baator must have its more neutral, Land-touched regions near Darkspine; Elysium has its tangled, bramble-ridden regions where the Traveler's Way dumps those with ill intent before they slide completely into the territory around Ecstasy; Yeoman has almost as many darker influences and malign traders from abroad as neighboring Tradegate; Broken Reach, on the other side of Plague-Mort's portal, is a sanctuary of sorts in the Abyss; even Heart's Faith in Lunia must have its seedier sections.

But your point is well-taken; the known gate-towns don't need to be the only routes between the Land and the Ring, or even the best-known ones. There's room in the infinity of the Concordant Opposition for as many transitive towns as the DM desires, though of course the more there are, the less important any one is going to be in a given campaign.

Generally speaking, I see towns in the Outlands beginning on the shores of Tir fo Thiunn (the most populous part of the inner Land, where many factols are from; the Spire is a destination of its own, not an origin) fully built in every imaginable shape, size, and theme. As their populations change and grow they slowly move toward the seventeen axial points, drifting toward the tainted lands bordering the Ring or the supposedly virginal lands in the center. If one town became more strongly aligned than one of the existing gate-towns, the portal would probably close in the established town and form, perhaps in a different shape, in the new one.

More likely, the established town would drift slightly Spireward and the newer town envelop the portal in its place. Or that might not be the correct phrasing either: maybe new terrain is created Rimward, and both town and portal move there. They might switch back and forth unpredictably, but this is uncommon; a town is a gate-town because it is on the razor's edge of one plane and the next already, and there's not much futher it can go without sliding all the way.

A boom-town that suddenly became more lawful than Automata would probably merge with Automata at first, becoming a single, larger town before dragging the whole amalgamation into Mechanus. The portal would then move to the next-most lawful town in the Outlands, or more accurately the town would move to it, the land formally surrounding the portal disappearing into the Ring.

If a town became so neutral that it moved all the way to the Spire it would probably disappear, seeming to merge into the mountainside, only to reappear as a new district in Sigil itself.

I think of the Outlands as a flat plane with sixteen funnels in a perfect circle, like the common depiction of a gravity well with space-time distorted by alignment instead of mass. Around the gate-town the plane is curved in the shallower, outer rings of the funnel; the gate-town is in the deepest, innermost part. Of course, Balanceward in the center of the ring of funnels is another one, terminating in the Spire. Hopeless and Bedlam are literally and figuratively built around spiralling depressions; Glorium has a literal funnel in the form of the Maelstrom in its harbor and the caverns leading to Yggdrasil's root; while around Spire, Excelsior, Fortitude, and (one might argue) Ecstasy the funnel is inverted, but still very literal. In most other gate-towns, the funnel is figurative, things being distorted in other ways than the topological.

Is this model too convenient? Probably. It's intriguing to think whose agenda it serves to create the illusion that the Outer Planes are a ring.