FA is evident often...people think they see 'protective' behavior when in reality it is FA. Dogs that are confident seldom if ever act out aggressively. Aggression generally comes out of that fight or flight instinct. <This isn't including the sport bite work or protection type training aggression, but general day to day life stuff.
Young dogs can't really decipher which is the right path to take so aggression happens with the lower threshold dogs. Higher threshold will wait and see, think and decide whether or not to react.
Seldom does aggression with a young dog come from a dominant mindset, but every now and then there is "that" dog that is extreme on the civil chart.
Insecurity is always fear based, no?
Onyx, my female is a bully. Bullies are usually not very confident and take advantage of the weak. Again, it is a fear based mindset.