Law was a genetic engineer, using one of the methods to carry out stages of solving genetic engineering problems. You in turn were his assistant, but it’s easier to say running errands

By selecting genetically modified organisms Law got something. And it seems due to the lack of fear and probably reason he decided to try it on himself by introducing the gene into vector

And as soon when he did this "trick" he got leopard ears and a tail «Why are you staring for?» He asked a bit annoyed