have somebody at your mercy
have (someone) at (one's) mercy
To have someone utterly under one's control, to the extent that one can force their actions. Please don't report me to the headmaster. You have me at your mercy! Once the gangsters were able to blackmail Susan, they had her at their mercy.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
have somebody at your ˈmercyhave somebody completely in your power or under your control: I’ve got you at my mercy now. What shall I do with you?
Farlex Partner Idioms Dictionary © Farlex 2017