at the mercy of
(idiomatic) In the power of; defenceless/defenseless against.
The ball game is scheduled for Saturday, but we're still at the mercy of the weather.
Human beings do not live in the objective world alone, nor alone in the world of social activity as ordinarily understood, but are very much at the mercy of the particular language which has become the medium of expression for their society. Edward Sapir
Things which matter most must never be at the mercy of things which matter least. Johann Wolfgang von Goethe
The creative writer uses his life as well as being its victim he can control, in his work, the self-presentation that in actuality is at the mercy of a thousand accidents. John Updike
A man gazing at the stars is proverbially at the mercy of the puddles in the road. Alexander Smith
The true purpose of the strong is to promote greater strength in the weak, and not to keep the weak in that state where they are at the mercy of the strong. Christian D. Larson
You are never to lose sight of nature; the instant you do, you are all abroad, at the mercy of every gust of fashion, without knowing or seeing the point to which you ought to steer. Joshua Reynolds