A dictionary definition of the word behavior is "manner of acting or controlling yourself". To ascribe behavior to a mathematical system is outside the probable intent of the definition but having spent a good bit of time in the company of such systems, I find behavior to be the best word available. Sometimes the behavior is surprising, sometimes it even appears willfully contrary. You may also catch me talking about systems prefering some state or wanting to go somewhere. I mean no offense by this. It just seems a convenient way of speaking.