After a week of Surviving, I love Minecraft. And what I love most are the Enderman. I like that they are the most powerful nocturnal monsters, but don't attack you without reason. Encountering an Enderman is always a rare sight for me; usually I have to dig underground to find them.
Here's my fan-made backstory:
Many Enderman are banished from the End to live in the Overworld. They must hide during the day and scavenge for materials at night, to protect themselves from humans once the sun rises. They are the most intelligent monster, able to craft dirt and other resources into small blocks to build with. Rather than craft more complex items, some Endermen will sneak through a human safehouse and steal from their chest, or even the house's bricks. They hold a level of respect for the other monsters.
When I find one, I don't try to kill him. I like to think that he's after resources as much as I am.