have (one's) knife in(to) (someone)

To make someone's life more difficult or unpleasant because one dislikes them or holds a grudge against them. Primarily heard in UK, Australia. Why do you have your knife into me? What did I ever do to you? I feel like he's had his knife in me from the moment I started working here. He always gives me the worst jobs and makes me look like a fool in front of everyone else. A: "Why do you have your knife into Heather? What did she ever do to you?" B: "Hello, did you forget that vicious rumor she started about me last year? Yeah, I'll never forgive her for that."