eating
have someone eating out of your hand have someone completely under your control.
1987Bernard MacLavertyThe Great Profundo One of my main difficulties is that I'm not good with an audience. There's guys can come out and have a crowd eating out of their hand right away with a few jokes.
the proof of the pudding is in the eating: seeproof.
what's eating you (or him or her)? what is worrying or annoying you (or him or her)? informal