The thing that the reader most likely had difficulty with was; He had trouble thinking of a bat as a character.
This question is from paragraph 5 of the book review titled "a backyard bat is an "abnormal" character".
Now, "Abnormal" is the opposite of normal, which means readers would have difficulty accepting it as a character in a book. However, the author further explains that although difficult to accept at first, the bat does become an interesting character as the story develops.
In conclusion the thing that the reader most likely had difficulty with when he began reading the book was that He had trouble thinking of a bat as a character.
Read more about paragraph interpretation at:https://brainly.com/question/24732717