Around here they are very shy and dive into the water at the first sight of a human. It is extremely hard to catch them, and sometimes it is even hard to get close enough to photograph them if they are by the water. You certainly don't have to worry about them chasing you down or being territorial. Like almost all wild animals, if they can, they will choose to flee. If they are cornered or harassed, they will defend themselves.
They tend to be grumpy, but only if you are dumb enough to grab them (like me). Here's a juvenile that I caught and released a few summers ago. The blood isn't from the snake...