Who are the minor characters in The Curious Incident of the Dog in the Night-Time? How important are they to Christopher?
Siobhan is a minor character in the book, however, she is incredibly important to Christopher. She is his teacher at school, but she also helps to provide guidance for him that he clearly listens to and respects. She is also the one who suggests he write this book, and much of his formatting comes from her suggestions. So, in that sense, she is critical to the story.
Reverend Peters is minor character in the book, but we see that he tries to help Christopher to process things that are very abstract, like the idea of heaven; we see this in Ch. 61. This is important to Christopher because his father is not really talking to him about the death of his mother, so others around him are helping him digest this information and "what happened" to her.
Mrs. Shears is a minor character in the book, but she is Christopher's neighbor, the owner of Wellington, and as we later find out, Mr. Boone's ex-girlfriend. So, she is important to Christopher if, for no other reason, that he cares about her dog and when he is murdered, he wants to know why.
Mr. Shears is another minor character in the book, but he has quite a lot of influence in Christopher's life, simply because his mother has moved away with him and when Christopher comes to stay with them, Mr. Shears appears to be very intolerant of Christopher. This causes Christopher's mother to leave Mr. Shears and move back near Christopher and Mr. Boone. Mr. Shears is important to Christopher because he is one half of the couple that changed his life.
Mrs. Alexander is a minor character in the book, yet the information she provides Christopher is critical to him figuring out that his mother is still alive. She also is a real friend to Christopher and does not judge him. She lets him be himself and that makes him feel safe.
Mr. Jeavons is a minor character in the book. He works at Christopher's school and often asks Christopher about his habits or comments on them. He's observant, noticing what makes Christopher feel safe, and then helping to explain those observations to Christopher. We see this when they are discussing Christopher becoming an astronaut and why he likes math, and having things in order.