Maybe I should really start on the Destiel fics, but then again I've only watched the first five seasons so. [Also, how do you post original work without lighting ruining the pic? Cuz I have no idea?]
“Satanism advocates practicing a modified form of the Golden Rule. Our interpretation of this rule is: "Do unto others as they do unto you"; because if you "Do unto others as you would have them do unto you," and they, in turn, treat you badly, it goes against human nature to continue to treat them with consideration. You should do unto others as you would have them do unto you, but if your courtesy is not returned, they should be treated with the wrath they deserve.”
Crowley fills the bookshop with his ruined plants instead of killing them. This is a way - in his mind - to comfort Aziraphale when he inevitably falls.