Concomitance is a relationship limited to two spirits. It is common between twins and somewhat comparable to soul mates. It means 'occurring together with something else'. Concomitance is an intense bond, often romantic. It can be cultivated positively or negatively. It is based on the tension between two conflicting personalities.
In spirit-human relationships, it may be found alongside a Partnership.
Concomitant spirits reside in adjacent Courts. These are currently Red-White and Black-Blue. Concomitance is most common in Red-White spirits, as the two Courts hold starkly different values (negation and self-restraint versus indulgence and excess).
Concomitance results in repetitive cycles in the Concomitant pair. When developed positively, this results in the Concomitant spirits being pacified, a desirable outcome as usually one or both spirits are powerful or dangerous. When developed negatively, the Concomitant spirits usually engage in repeated attempts at murder or torture of their other half.
Concomitance is seen largely as a coincidental relationship, begun when one spirit is birthed with spiritual energies belonging to another (as is the case with Lilibell being born with Althea Altair's heart) or when two spirits are assigned as Mirrors. One spirit usually initiates a positive or negative Concomitance, at which point the other has the option to reciprocate.
Concomitance ideally disperses powerful energies that spirits possess, somewhat like Companionship. Through positive Concomitance, these energies are subdued, the more violent or dangerous spirit calmed by their Concomitant. Through the negative, the violent energies are usually directed or reserved for the Concomitant. (A spirit such as Alynah Blake, for example, could use a Concomitant in order to curb her violent sprees.)
People who do not do spirit work of any sort are unlikely to have a Concomitant relationship. For those that do engage in such works, if the necessary restrictions are met (belonging to adjacent Courts/gods), Concomitance can begin very easily initiated. One can refuse the relationship or be refused, however.
People who engage in a Concomitant relationship are likely to take the role of the placating Concomitant. Spirits can be difficult to interact with, and they can be dangerous to themselves and others - a Person engaging the role of a placater in this sort of relationship would take on the responsibility of helping to soothe such a spirit. It is possible for a spirit to be soothing toward a human, however - this would likely be for those with intense or difficult to handle emotions.