I need to make my pet follow only it's owner but how?

I wasn't aware pets could follow anyone except the owner, but since I started modding I haven't actually played Minecraft much for a long time. Haha. If you want to change how they behave, you will have to tinker around with the entity's AI. There's one called EntityAIFollowOwner. You can create your own AI based on it, then during the EntityJoinWorldEvent you can remove the old one and register yours. Here's a decent tutorial that covers the basics:

 

http://www.minecraftforum.net/forums/mapping-and-modding/mapping-and-modding-tutorials/2281106-tutorial-how-to-change-an-existing-mobs-ai