I'm a fan of inserting 'levers' into territory concepts. From an extremely abstract standpoint, this can be a hook. But if you want to make it slightly more concrete, you can assign point values to different shapes, depending on your needs: a fork, for example, would be a single territory that is dependent on two territories for your objective (defense, production of money, travel), or a fulcrum, that tilts another territory when it is moved, or various shapes of triangle points, such as a square that pulls two territories along a tangent into some relationship predetermined by your rules (economic benefit via alliance, the tangent point providing mutual defense in both points by virtue of the square angle, etc.)
The point values would depend on your own needs. This is a complex, vague system, I know, but you would have to have several people hash this out, instead of one engineer, or else you'd get a very rigid system for one limited scenario.
And of course, you'd have to name the geometric territory relationships different things appropriate for your theme.