What is the Green God(Dream)?

Who is Dream? What is his origin? Where did he come from? He doesn't have much of a backstory, does he. But then, he isn't the only 'Dream' to walk the earth, now is he? What is this race, and where do they exist from? This isn't much of a story, more of a focus and a slight bit of journal style entries for a few of them.

Disclaimer: I have nothing to do with the Dream SMP, this is not canonical. Also, the fanart is not mine. I wish I could give proper credit to the creators of these images, but sadly, I can't tell who is the original artist, and who isn't. If you read this, and you did create it, I love your work!