be putty in (one's) hands
To be easy to control or bend to one's wishes. (Putty is a very malleable material.) Oh, come on, Julia is putty in our hands—we can definitely get her to help us with this prank.
be like putty (or wax) in someone's hands
be easily manipulated or dominated by someone. 1975 Sam Selvon Moses Ascending Bob was there, and I gave him a little bit of crumpet, and afterwards he was like putty in my hands.