I have a question about what a character in a certain book is talking about during a certain passage of said book, and I am wondering if that would be on-topic here. If not, what site could i ask it on?
It depends on the question. If you are asking about the meaning of a word or phrase in context and you can show that you have done some work to try to figure it out on your own (e.g., you've looked up the word or phrase in a dictionary and can explain what it means), it is probably on-topic.
On the other hand, if you are asking what the entire passage means in the context of the story, that would not be on-topic. I don't believe we have a site for that, but you could ask in chat.