Our son, LR, has always had incredible verbal skills. When you combine a "good ear" (for music, sounds, anything), with an ability to mimic sounds well enough to easily end up in the principal's office for doing teacher impressions, and attach them to an amazing memory you end up with a child who knows one heck of a lot of words. He had even begun learning how to read when he was about 3 1/4 with a natural ease that was just wonderful to watch. Words became just one more toy on his shelves that he wanted to take down and play with.
For some reason, about 5 or 6 months ago, he just stopped. Completely "cold turkey." He would sometimes still want his letter and word oriented videos, he would still, sometimes, be willing to tell me what sounds individual letters, but overall he was clearly just not interested. The number of books he wanted me to read to him also declined.
Then, the other night, my wife started to read a bedtime story to him and he took the and simply began reading it. Well. Very well. He certainly stumbled over the big words (like "especially;" heck, I know adults who would stumble over that one), but he just asked for help whenever he needed it and then went on. He ended up reading her the whole book!
While he definitely needs some help in some areas, it's nights like that that help me get through some of the other days. Thankfully, nights like that are definitely in the majority.