n.an unexpected and inexplicable change in something (in a situation or a person's behavior, etc.)

Vagaries of the Molecular Clock
Vagaries of visual perception in autism.
The vagaries of variegating transgenes
Vagaries of conditional gene targeting. Nat Immunol 8(7):665-668
Colloquium Paper:Vagaries of the molecularclock
Vagueness's Puzzles, Polysemy's Vagaries
Morality: Its structure, functions, and vagaries.
The vagaries of sex bias: Conditions regulating the undervaluation, equivaluation, and overvaluation of female job applicants.
An overview of pheochromocytoma: history, current concepts, vagaries, and diagnostic challenges
The case of the missing data: methods of dealing with dropouts and other research vagaries.