Capricious (a.): Governed or characterized by caprice; apt to change suddenly; freakish; whimsical; changeable.
Perfidious (a.): Guilty of perfidy; violating good faith or vows; false to trust or confidence reposed; teacherous; faithless; as, a perfidious friend.
Perfidious (a.): Involving, or characterized by, perfidy.
Capricious (s): Determined by chance or impulse or whim rather than by necessity
Capricious (s): Changeable
Perfidious (s): Tending to betray; especially having a treacherous character as