Can't wait til Chapter 13. Rebecca did bring Travis <3, and Charlie does seem a bit shocked. Was he expecting Rebecca to bring a girl so that he can continue hiding in the closet? Its good that they're going for dinner, I would love to see more Derek's adorable stupidity.
Since this story is largely Derek's narration of past events, I'm sure he is beating himself up for not realising the clues earlier. This is probably why he is putting so much emphasis on the little things like the Charlie's 'blushing' and 'excitement', which puzzled him in the past. Really fun to read