Arthur yells at Merlin, pushing him away in the process. When the unexpected strikes, he's faced with the possibility of them being the last words he ever spoke to his best friend.
AKA, Merlin gets bonked on the head and Arthur panics.
Bilbo had a sudden, cheerful realization. “Oh, my, this must mean you’ve already dealt with the problem of the dragon without me!”
Bofur frowned. “Bilbo, no–”
“Sorry, you haven’t dealt with the dragon?”
--
Or: the Consort of Erebor loses about seven years of memory.
