I guess it's a school thing. He will be exposed to fiction, be required to read it and be required to deal with the emotions. I'm a bit worried about that one, as it's not in a protected environment the way our bedtime reading would be and he can't really say no. I hope he has time to become more comfortable with it. That's why I'm asking for other's experiences - if there children were like this, is there a reason to be worried about forced exposure in school, did they get in trouble for refusing to read a book they were supposed to read or to participate in class discussion or write an essay, were they considered behind in language arts because they had trouble with this...at what age/grade wwas it an issue, if at all? I am ready to be told not to worry yet!
Well, since they spend the first 2-3 years learning to read they don't do a whole lot of discussion of themes in literature until age ~9 at the youngest, and it's really not until 10 or older in the US that they do much of this. At least in our schools, there's also a mix between fiction and non-fiction in the anthologies. Today dd's class was reading about honey bees. Your son is still 5, his ability to handle emotions will mature in the next several years. Really.
At 5, our dd absolutely refused to read fiction that was 'scary'. The Magic Treehouse books were far too scary, in her opinion. When I was making up stories, absolutely nothing scary could happen in them. I remember starting a story about a little fish in the ocean who went to fish school. I started to add something about how the little fish were learning about the shark who lived nearby. Dd stopped me and said "no, no sharks. Only good things happen in this story." Then she went on to guide me into telling a story that essentially was "the day in the life of a preschool fish". And yet, 2 years later, she read the entire Harry Potter series.
There's a pretty big intellectual leap between age 5 and 7 where children learn the structure of stories in their culture. At 5, stories are really scary because they have no idea that it's going to be resolved. By 6 or 7, they've learned that the conflict is going to be resolved. One of the things that early chapter books do is introduce children to this structure. Books like the Magic Tree House books have a very very predictable structure. Each of the 47 MTH books are 10 chapters. Jack and Annie go on the adventure in the first chapter, they come home in the last. The climax comes in chapter 9. Each chapter ends on a bit of a cliff-hanger. While this kind of predictability is torture for parents, it's good for children who are learning to read. They don't have to figure out twists in the plot. The plot unfolds in a predictable fashion.
It's OK if he stays inside his comfort zone. He's only 5.