Tethers are the inscrutable lines that tie beings and objects together with Meyda. Requiring at least two sources of Meyda and at least one unique identifier. A Soul will always function as a unique identifier that informs the Tether of its purpose. However a False Soul may be used to tether one or more non-sentient objects or creatures to each other. Tethers made between two Souls are powerful, allowing significant Meyda-flow limited only by the processing power of the Souls in question. It is for this reason that contracts of many kinds are not to be held lightly. Especially the more fundamental Contracts of Birth and Blood. They literally tie souls together, often until death if not longer, and can be the cause of many strange phenomena.
Strands
Strands are much simpler tethers. Those that reach out and tell the Meyda where to go, what to heal, what to harm. Strands may exist for but a moment, or for as long as Meyda flows through them, but once their purpose is ended they disappear as quickly as they came. The connection between a set of Minor Stones and the World Stone in an Astrostone is simply a Strand. It is powered by the stone itself and perpetually ties the two sources until one theoretically runs out of Meyda. If the stone is removed from the Meyda-circle or the more modern iron ring assembly that informs the Strand it immediately dissipates.