"Rikki-Tikki-Tavi" is written in the form of a fable, a story about intelligent animals that interact in the human world. Since the story is meant for children, Kipling wrote in an informal style:
He spent all that day roaming over the house. He nearly drowned himself in the bath-tubs, put his nose into the ink on a writing table, and burnt it on the end of the big man's cigar, for he climbed up in the big man's lap to see how writing was done. At nightfall he ran into Teddy's nursery to watch how kerosene-lamps were lighted, and when Teddy went to bed Rikki-tikki climbed up too...
(Kipling, "Rikki-Tikki-Tavi," cs.cmu.edu)
Kipling uses strong descriptive language to show the world and its inhabitants; Rikki-tikki's curiosity is used to inform the reader about the house and the garden, where the snakes live. This natural exposition allows the reader to discover the danger of the cobras just as Rikki-tikki does, and to feel fear for his life as his fighting skills have not yet been demonstrated. While the story is written simply, it does not talk condescendingly to the reader, instead forming its style as if recorded from the spoken word; the inherent evil of the snakes is contrasted with Rikki-tikki's drive to protect his adopted family, and so the story contains a classic clash between good and evil.