I really like this verse. It packs a whole lot of punch. Have you noticed the following in Mark 5:15?
"And they come to Jesus, and see him that was possessed with the devil, and had the legion, sitting, and clothed, and in his right mind: and they were afraid."
"him that was possessed with the devil"
His inner being was different and free from what had enslaved him.
His actions were different; he was no longer screaming and causing fear and destruction.
His dress was different; he now wanted to cover rather than uncover his body, and in a wholesome manner.
"in his right mind"
He thought and talked differently than before he had met Christ. Now he posessed wisdom and normality as God views normality.
"and they were afraid"
Others who haven't been changed by Christ often don't understand and are sometimes scared of how different we are. It's as if they would rather we remain as we were before meeting Christ.