quicksilver (adjective) fickle: vacillating, blowing hot and cold
Sinonime: arbitrary,
capricious,
changeable,
cheating, coquettish, double-crossing, faithless, fitful, flighty,
frivolous, inconstant,
irresolute, lubricious,
mercurial, mutable, quicksilver, sneaking,
temperamental, ticklish, two-timing, unfaithful,
unpredictable,
unstable, unsteady,
untrue,
variable,
volatile,
whimsical, yo-yo
Antonime: aware,
cognizant,
constant,
faithful,
reliable,
stable,
steady