Hello,
Ok, you got the roo to protect ? The roo will protect the hens alright but first he needs to establish his place among the flock. He will probably get "pecked" now and then and he will get agressive with the hens for being bullied so to speak but this will not last long. The Roo will "RULE" eventually and that is what has to happen. The Rooster is always at the top of the totem pole and he will always be. The hens will back down and let him be the ruler of the flock. You don't need to be worried about him hurting the hens and if he does get agressive, let him be.
There has to be a dominant one in the flock and there is constant fighting from the hens to establish that position. But now that you have a Rooster, the previous dominant hen will have to step aside and there is no question about that from the Rooster.
It's natural for this behavior. No need to sharpen your axe....leave the axe in the shed for racoons.....
My Rooster was the best leader with the hens and he would protect them to to the point that when they were all outside free-ranging, he would gather the hens up when it got dark and he wouldn't go inside the coop until all the hens were home safe. If there were one stubborn hen who wanted to get one last crickett, he would go after her and chase her back to the coop...It is one of the most interesting things I've ever seen. I have learned allot from raising chickens and I learned that you don't interfere with the order.
Leave them be and watch and learn. There are some Roosters who will actually kill a hen for not abiding to the rules but this is very rare.....Now when you put two Roosters together, that's another story. Just relax and enjoy. If you want to get close to your roo, pick him up everyday and hold him for a few minutes...he will start trusting you and learn that "you" are the boss of him. My roo loved for me to come pick him up and scratch his head. he was also HUGE....you just can't be afraid of them...good-luck.