STill don't know, right. It's pretty clear, I think, that it relates to what the demon wants, and why Sam is so special (as are the other children whose mothers died on their 6-month birthdays), but we don't know what it is.

John's so damned hard on his sons.

If you are in the mood for fic, the story tripoli8 posted today has no spoilers beyond 201. And both killabeez and destina have posted stories that take "Devil's Trap" and go to really AU places with them. Des' is very dark, though.