From Pluralpedia, the collaborative plurality dictionary
gatebridger (n., adj.)
Applies toheadmates
Coiner NeonWebb/WitchyRose

A gatebridger is a system member who connects the gates (or gate-like things) of different systems, both within and outside of the body.

A gatebridger could just be for travel between sidesystems/subsystems, or travel between separate systems in separate bodies.

Gatebridgers could connect realms, headspaces, or they could simply connect parts of the same headspace to each other to make travel faster.