Endermen , as soon as we see them we either say "Ah an Enderman ! Run take all your favorite blocks" or "Yay I'm going to kill it and get ender pearls !" Now why do they not like it when we stare at them ? Probably because if you are going to kill it to get pearls , you might stare at it a while , waiting for the right moment to Pounce ! So see it this way , you are walking around , some guy is staring at you , you look away then five seconds later he thrusts a sword at your back , and dances on your corpse saying " Yay I can get an ender pearl now ! " then he sticks his hand in your chest and pulls out you soul , a beautiful pearl . Now imagine your his son you watched this happen , your jaw drops of surprise then he turns around and looks you in the eyes , Now you might avenge your father , witch he did , or you could be a wuss and run away , he avenged his dad , and later in his life he told his children the story , they did the same and so on . Now think of it this way you were told of this happening and some guy with bloodshot eyes is staring at you with a bloody sword , What would you do ?