YES!!! It will take some time, and the article that FeebysOwner
linked is VERY good, but things will get back to normal. The main things is, HE IS HOME AND SAFE!!!
So happy he made it back home, i know the feeling of missing a cat outside you can think of anything that can go wrong, he was gone quite awhile 10 days.... Is the brother acting normally with him again? I had 2 of my kittens got out a few weeks ago I basically couldnt do anything but keep looking for them to come back... Luckily only gone a few hours we found them in the neighbors yard.