The phrase deus ex machina (Latin (literally "god out of a machine") describes an unexpected, artificial, or improbable character, device, or event introduced suddenly in a work of fiction or drama to resolve a situation or untangle a plot (e.g. an angel suddenly appearing to solve problems)
It is arguable that Litvinov, had he met with civility and those supple conversations à deux in which trained diplomats excel, might have stopped the war... --William Manchester, The Last Lion Vol. 2, page 458.
pas de deux is both the singular and the plural form; both forms are pronounced In ballet, a pas de deux is a dance sequence for two dancers. pas de deux a dance in ballet performed by a man and a woman. (French; "step for two") Dance for two performers. A characteristic part of classical ballet, it includes an adagio, or slow dance, by the ballerina and her partner; solo variations by the male dancer and then the ballerina; and a coda, or conclusion, with both partners dancing together to display their virtuosity. Celebrated pas de deux occur in Sleeping Beauty, Swan Lake, and Giselle