cat's-paw
A person who is used by another to achieve some end, especially in a duplicitous or cynical manner. Taken from a fable about a monkey who uses a cat's paw to retrieve chestnuts from a fire. I thought that Jake really loved me, but in the end, I was just a cat's-paw so he could stir up jealousy in his ex-boyfriend.
keep (one's) paws off (something or someone)
1. To refrain from touching or handling (something or someone). Usually said imperatively. You kids keep your paws off those cookies. They're for after dinner! I told you I wasn't interested, so keep your paws off me, you creep! That car is brand new, so keep your paws off!
2. To refrain from becoming involved with or attempting to take or control (something or someone). Usually said imperatively. That rotten bank had better keep its paws off my land! Listen, buddy, keep your paws off my sister, you hear?