I have had a cat do that also. He was a terror. He would stalk only one cat, Weezie. Finally I took him to the Vets to see if anything was wrong with him. Vet did blood work and a good over haul. Not a thing was wrong, so the Vet put him on Amitriptyline for a couple of months, it helps to modify behavior. And it did the trick. Tyler got one pill a day and now is doesn't stalk or attack Weezie, just catnip toys. Thank goodness. Or he would have had to been history.

Stella