(to be) at the mercy of [sb/sth]

"At the Mercy of" is a Prepositional Idiom

Explanation:

A prepositional idiom begins with a preposition and functions as an adjectival or adverbial phrase in a sentence, often describing conditions, relationships, or circumstances.

In the case of "at the mercy of", the idiom describes a state of dependence or vulnerability, answering questions such as "under what conditions?" or "in what state?". It modifies a verb or provides additional information about a subject.

Examples:

The sailors were at the mercy of the raging storm.

(modifies "were" – under what conditions?)

Without proper funding, the project is at the mercy of its donors.

(modifies "is" – in what state?)

The villagers were at the mercy of the invading army.

(modifies "were" – under what conditions?)

• To be completely under the control, power, or influence of someone or something, often in a vulnerable or helpless state.
• To be dependent on someone’s decisions or actions, especially when they may not act in your favour.

• After the car broke down, they were at the mercy of the harsh desert conditions.
• The villagers were at the mercy of the invading army, unable to resist.
• Without legal representation, she felt at the mercy of the court system.