I Have the Depressing Villain Wrapped Around My Finger

A System suddenly appeared and told me to make the villain miserable. What a coincidence, making people miserable is my specialty!

My senior brothers and sisters say they're about to lose it whenever they have to bring me along.

I order the villain to knead my shoulders and legs, or send him to fish at the bottom of the lake in freezing weather...

Why is the villain looking at me more and more strangely?

He must be jealous of me. Then let's make the whole world miserable together!

(The heroine is six and the hero is nine at the start, and they'll grow older later. I want to write childhood friends with a bit of a growing-up-together feel, so the main plot won't rush. There'll be more everyday moments between them.)