One of themes for Rikki-Tikki-Tavi is that you need to help others in need. The reason I know this is because all throughout this story, there are people, or animals, helping each other. You should especially help someone who has helped you before, which is what most of these people (and again, animals) did. Even though you think it was mainly Rikki helping people, there were other people too. But Rikki probably did help the most. But Rikki has been mostly very helpful to the family because they saved him from the stream. For instance, on page 240, it states that Nagaina is in striking position, ready to kill Teddy in front of his father and mother. But Rikki tries to deal her egg for Teddy’s life. It works and Rikki chases Nagaina into her