D. Gray-Man: The Big Picture

I originally started the following document for my own benefit at Chapter 220, so I wouldn't have to go back and reread the last three chapters every time one came out, and so that I could try and figure out the big picture of what has been going on in D. Gray-Man based on the rather sporadic comments the characters dole out. It incorporates information found throughout the manga, and I've added on to it as new chapters are released. However, I decided that others may find this information useful, so I'm posting it here.