temperamental

My old car is very temperamental and often refuses to start on cold mornings.

(Chinese) 我的旧车非常“任性”，在寒冷的早晨经常无法启动。

The artist was known for being temperamental and frequently walked out of rehearsals.

(Chinese) 这位艺术家以喜怒无常著称，经常在中途退出排练。