I believe that no one can predict the future. What might happen could be written in the stars, but I guess no one could decipher those writings. Even sophisticated scientific methods and devices couldn't accurately tell when earthquakes or volcanic eruptions will occur. These couldn't even measure the extent of damage a huge typhoon will bring.
Just like events, people are unpredictable too. They can be consistently behaving in a certain manner, but you might be surprised to see their other side when induced or provoked. Never judge a person, as you may never know what they can do - to you.