When his headaches developed, Nick became bad-tempered and even violent.

尼克的头疼起来时，他变得焦躁易怒，甚至暴躁。

《柯林斯英汉双解大词典》

He's a strange chap. Usually he's very pleasant and reasonable, but there are times when he gets very bad-tempered and almost violent. He's got a Jekyll and Hyde personality.

他是个很奇怪的家伙。他常常很快乐而且明白事理，但时而又脾气很坏甚至粗暴。他是个具有双重性格的人。

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His father, a violent-tempered autocrat, was appalled to discover that his eldest son, far from being a puritanical boor like himself, showed every sign of developing into a charming, fun-loving youth, with advanced aesthetic tastes.

ECONOMIST: Historical biography

But unlike Defoe's noble hero, Selkirk had been cast away for good reason: He was a violent, foul-tempered guy.

FORBES: Castaway