A sound temperament is a must in a German Shepherd Dog (GSD) By sound, I mean a disposition where one minute you can let a protection trained GSD play alone with your 5-year old child, pull on its ears, pet its head, tug on its tail and NEVER-EVER be in harms way; while the next minute, it should turn into the "terminator" and crush its enemies as soon as it senses an intruder...