Quad

A quad is a four-person polycule. The internal shape can vary widely. A classic quad is two couples whose members all become partnered with each other across the original pairings — sometimes called a quadruple or square configuration. Other quads have only some of the possible internal edges: an N (four people in a chain), an asymmetric four-way with three close edges, and so on.

Quads can be very stable when each of the internal pairings has independently good fit; they can be very unstable when one pairing was forced or assumed. Like triads, quads form in two patterns — organically, from existing pairings that grow together, and deliberately, from two couples seeking each other out as a unit. The deliberate-formation pattern shares the structural risks of unicorn hunting at a larger scale.

Practical complications of quads include calendar logistics (four people coordinating shared time is materially harder than three), and the fact that any change in any one of the relationships ripples through the rest. A break-up of one edge in a quad does not necessarily collapse the structure, but it always reshapes it.

Larger polycules — five, six, more people — follow the same pattern as quads but with more edges and more change-sensitivity. Past a certain size, the polycule becomes less a discrete unit and more a connected neighbourhood in a larger network.