so here we go....we have a 2 year old Rottie. we've had him since he's about 4 weeks old. extremely intelligent, quick to learn new commands, excellent with other dogs, excellent at dog park, excellent behavior at home...But, there are a few issues we are currently encountering. 1. he seems very aggressive while on walks in our neighborhood, if he sees anyone he notices them immediately and is cautious of them and if they get close he growls and wants to go towards them, he does this to just about anyone he sees. I don't know if is out of fear or actual aggression or protective instinct of the breed. He does the same thing when he's in the car with us, if anyone comes too close to the car he goes berserk. 2. while out on walks he will walk half way up the block and then stops and wants to turn around and go back the other way, but if I take him off leash he follows me once he sees that I'm getting far from him. I don't like forcing him to walk a certain distance if he refuses and wants to turn around. he is also extremely nervous and jumpy, he freaks out if he hears any sudden sounds like, motorcycles, any loud motor cars, any sirens from police, fire, ambulance etc. fireworks of course, does not like skateboards, motorcycles, anyone on roller blades, or anyone on a bicycle. sometimes when at home he'll freak out for no apparent reason and goes to his bed in our bedroom and just lies there for approx 30 minutes or so. I have no idea why he's showing this type of behavior...any help is greatly appreciated.