mutual, reciprocative, reciprocatory, correlative, interactive, interchangeable, complementary, interactional, inverse, retributory, more...

unilateral, independent, nonreciprocal, one-sided, unrelated

multiplicative, additive, exponential, geometric, logarithmic, quadratic, polynomial, rational, irrational, more...

negative, polar, exact, own, simple, non, true, direct, mathematical, homologous, harmonic

goes both ways,   each othe,   inverse operation,   one over,   mutual pronoun,   that goes both ways,   in each other,   on each other,   feeling is mutual,   inverse number