Every living being in Terrybiel bears the imprint of the magic that flows through it and is unique to it. In some, it remains dormant, in others, it blossoms into what scholars call Ethren.
For most beings in Terrybiel, Ethren is imperceptible, and they live without ever being aware of it, their imprint diffusing into the magical flows flooding the continent or serving to amplify that of beings whose imprint has blossomed. (Familiars, Tears, Half-Blood.) For them, Ethren becomes visible and tangible to their senses.
An Ethren is three things at once.
* A color.
* A smell.
* A sensation.
Young familiars are particularly sensitive to it. The Ethren of their Heart resonates within them like an inner melody, a frequency with which they vibrate in concert and harmony, guiding them towards their other halves (The Call).
Over the years, knowledge of Ethren has evolved, and there is no doubt that further discoveries will be made over time.
1) Identifying without error.
An Ethren functions somewhat like a living signature. Their uniqueness allows magical beings to confirm the identity of their peers, but also to seal contracts or authorize access to certain places.
2) Orienting and finding your way.
Ethren trace “threads” in the magical flow. You can follow the lingering presence of a recent Ethren, locate an ally, or sense if a loved one has passed by. Familiars instantly recognize the twin note that corresponds to them.
3) Tuning magic and artifacts.
A spell “takes” better when it is tuned to the caster's Ethren. Certain objects only open to the bearer whose Ethren matches the seal imprinted on them. For example, Elianna's sword only ignites when she touches it.
4) Protect and/or conceal.
One can anchor their Ethren to bless/protect a place (it will “recognize” its own) or, conversely, veil their Ethren to go unnoticed. Veils are costly and tiring over time.
5) Heal and/or diagnose.
Healers “listen” to the state of an Ethren: a harmonious aura, a cracked note, a crackle (exhaustion), or a dissonance (corruption). Treatment often consists of retuning the Ethren: rest, rituals, anchoring, contact with the familiar.
6) Swear and bind.
Certain oaths bind the Ethren: breaking one's word creates a dissonance that is immediately perceptible to the other party, and sometimes to the sanctuaries that house the oath.
7) Communicating subtly.
Between attuned beings (especially Tears/familiars), a brief exchange of Ethren is enough to convey emotion, intention, or warning like a pulse of light or scent.
Ethren veils wear down the wearer and dull their magical senses over time.
Magical storms or places saturated with magic interfere with the reading of Ethren imprints.
Attempting to imitate another's Ethren almost always leads to dissonance: migraines, nausea, or even a rejection of magic.
Leaving too clear traces of Ethren can make you traceable; experienced Tears learn to cover their tracks cleanly.