Man, all my favorite AUs have already been suggested. How about:

-that time when 5 and 10 got bodyswapped and it was all down to 2 to find the cure.

-4 and 9 are long-lost siblings! What is the tragic story of their past? Will they ever be reunited?

-Why was 6 afraid of 7? (:-P)

-What's it like when 1 is the supreme ruler of the world with 3 as their consort? What happens when 8 leads a rebellion to claim the throne?