Nezuko is the main character's sister. In the original series, she doesn't talk after she gets turned into a demon, except for one scene at the climax of the first season where she speaks internally. For the abridged, we decided we would let her "talk" more, by utilizing inner voice, essentially, her thoughts. This means if Tanjiro does some stupid shit, we can write some lines for Nezuko to insult him. We've chosen for her to be a short-tempered smartass, who basically only keeps Tanjiro around for her dirty work. Feel free to improvise on lines! Have some fun with it.