a Jekyll and Hyde

Jekyll and Hyde

A person whose personality drastically changes between good and bad. A reference to the main character in the book Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson. Ever since Kyle became a teenager, he's turned into a real Jekyll and Hyde, and it's impossible to anticipate his mood at any given time.
See also: and, Hyde, Jekyll

a ˌJekyll and ˈHyde

a person with two separate personalities or ways of behaving, one good, pleasant, etc. and one evil, unpleasant, etc: He’s a real Jekyll and Hyde. At home he shouts at his wife and children all the time; at work he’s always charming and friendly.This comes from a story by Robert Louis Stevenson, Dr Jekyll and Mr Hyde, in which Dr Jekyll takes a drug which separates the good and bad sides of his personality into two characters. All the negative aspects go into the character of Mr Hyde.
See also: and, Hyde, Jekyll
References in periodicals archive ?
It was a game of two halves, a Jekyll and Hyde performance.
Funke would refer to him as a Jekyll and Hyde because of his sudden outbursts.
At least once a week, usually more often, a patient in my clinic describes himself to me as a Jekyll and Hyde.
The transformative effect, however, is not purely pharmacological: for many a Jekyll and Hyde has told me that a quantity of alcohol taken as beer does not have the terrible consequences for his character as the same quantity taken as whisky.
I've heard "He's a Jekyll and Hyde character" as often as I've heard "I'm a Jekyll and Hyde character.
As for the person who claims that her lover is a Jekyll and Hyde, the metaphor serves to preserve and justify her love for him, despite all the evidence that he is unworthy of it.
Having a split personality, schizophrenia, is not a splitting of the personality into multiple parts, not a Jekyll and Hyde phenomenon, despite the popular hold of the Robert Louis Stevenson story.