dual nature; two-sidedness; two-facedness
Refers to a person, thing, or concept having two contrasting aspects or faces, often with a nuance of contradiction or hidden side.
I'm surprised by his dual nature.
This policy has two sides to it.
Compound of 二 (two), 面 (face/side), and 性 (nature/character). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for abstract qualities.