Story Recall is one of the oral expression subtests of the WJIII. There is no reading involved in it (the examinee listens to the story, and then re-tells it from immediate or delayed memory), which makes one wonder about expressive/receptive language challenges (yes, even with a really high VCI).
One of the differences between fiction and non-fiction is the narrative thread, which is much more important for fiction and history than for STEM-type non-fiction.
His reading fluency is also not as high as you might expect for a VCI in the 99th %ile. Plus, reading one sentence at a time is not as exerting as sustaining attention, reading rate, and comprehension through multiple paragraphs, pages, and chapters, so this may not be representative of his level of fluency for extended text. The general behavior of reading aloud in his head that he describes is usually more characteristic of readers who are not truly fluent. The amount of effort expended then becomes "worthwhile" only for high-interest reading.
My late reader also selects leisure reading (especially fiction) levels below what I know to be the instructional level, and also reports odd challenges when tired, such as not being able to articulate clearly when reading aloud ("I can only do one thing at a time."). And likewise prefers books with many illustrations.
