sandra f. johnson

I'm not looking to acquire a puppy but I was just curious about choosing one.
How does one tell which puppy in the litter would be better suited for personal protection and guarding? Would it be the more aggressive puppy, the more outgoing pup, the more social pup?
I know it surely wouldn't be the shy one or the submissive one. If I had to guess, it would be the dominant one.
I would imagine there are many people who pick a pup mostly because they are cute but when the dog grows into a young adult, all it wants to do is lay on the sofa and the pup's owner thought the dog would keep strangers away. There must be a way to know.