I came up with a bit of background about Creepers that I usually use on RP servers, or joke about on regular servers. I just thought I'd post it and get some feedback:
Long ago, a world was created by the god Notch similar to Earth (Minecraft Earth) in which not animals, but plants prevailed. An intelligent race of plants evolved in this world. You know them as creepers. After thousands of years of conflict, the race was unified as a single unit known as the Empire of the Royal Green, or simply the Empire for short. Two classes of creepers existed - the humanoid creepers, who were usually nobles (since they were able to easily manipulate the world around them), and the lesser-evolved four-legged creepers who were usually the common citizens subjects of the nobles. The Empire had a fair government, and poverty was nearly non-existent. However, one day, the Blue Gates appeared in the depths of the earth of this world, and the forces of Darkness began invading the Empire. The nobles, who were not the best fighters, sent legions of willing subjects to fight the zombies, skeletons, and spiders that threatened their homeland. The four-legged creepers were equipped with a natural ability to explode, a simple way of reproducing that scatters spores all over which in turn develop into new creepers, so they used this ability to their advantage. However, the newly deposited spores, as usual, contained the entire memory of their parent (which is why history was so easily remembered during the Empire's reign, since all creepers have a memory back to the point where their ancestry began). This started to become a bad thing as the subjects became more and more paranoid that the nobles were simply using them, and as the numbers of paranoid creepers increased, so did the talk of conspiracy. It was only natural that eventually, the subjects, now in extreme numbers, began to rebel against the nobles. The nobles, unsure of how to react, hid deep underground, where they discovered the Blue Gates and the power they held. They realized the strange cage-like rock arrangements were used by the forces of darkness to send minions from world to world. While they researched the Blue Gates, the nobles were caught off guard by a visit from the legions of subjects attempting to take them down. In a wave of desperation, the nobles escaped into the Blue Gates, followed by the hordes of creepers willing to kill them at any cost.
The Blue Gates led the creepers to Earth, a world populated by humans and animals, and they soon realized the forces of darkness had invaded this world too. Unable to escape through the irreversible Blue Gates, the nobles mingled with the locals. The subjects, who were not very bright, noted the humanoid shape of both the humans and the nobles and assumed them to be one and the same. That is why Creepers are so aggressive to humans.