Some additional context:
The default action of "Sad" and "Angry" is typically a down vote (-1). However, I have disabled all down voting on the site to avoid the issues that causes.
Reactions are used across the site. It uses the forum software's system. Reactions in Stories are no different to reactions in the Forums. People in the forum use "Angry" most often when they are angry with the creator of a post/content or that they said. Most people view it that way as that is the internet 'default' so to speak.
The reasoning behind the rankings
Like (+1) - person liked the post/content.
Love (+1) - person really liked the post/content
HaHa (+1) - person found the post/content funny
Wow (+1) - person was surprised by the content. (This could got either way, we acknowledge. good or bad surprise. but we emphasize the positive)
Sad (+1) - person was saddend by the content. We made this positive because most times people use this reaction it is support the poster of the content
Angry (0) - Person was upset by the content or the person posting the content. This was made neutral because pissing people off is not a plus.
I read It (0) - This is an acknowledgement that the content was read. It was made neutral because if someone is flagging it as read, it's just an acknowledgement. If they liked it they would have liked it. if they were angry about, they would have chosen Angry. I've seen it most in forum posts and not on stories/chapters.
@Headstall, I can see not liking the "I read it". I'm not fond of it myself when I see it on stories/chapters. But you can view it as an opportunity. Perhaps that reader didn't click with the chapter for whatever reason.... but they still took the effort to acknowledge they read it. Engagement comes on many levels and we can't all get everyone, every time.