Feelings noun – Emotional or moral sensitivity (especially in relation to personal principles or dignity). Mood and feelings are semantically related. in ambience topic. In some cases you can use "Mood" instead a noun "Feelings".
In Kantai Collection fic Eternity many of the lines are colored blue or red, a few times just to differentiate the speakers, but most of the time it is used to show the mood or feelings regarding the described subject.