He is a complicated man ——moody, mercurical, with a melancholy streek.

他是一个性格复杂的人——喜怒无常,反复多变,忧郁寡欢.

He became moody and unreasonable, flailing out at Katherine at the slightest excuse.

他变得喜怒无常、不可理喻，为点鸡毛蒜皮的小事殴打凯瑟琳。

Edwards was a dangerously volatile character.

爱德华喜怒无常，十分危险。