* Revenge: Nag and Nagaina were responsible for the death of Teddy's father, a previous resident of the bungalow. They hold a deep grudge against the family and want revenge for his death.
* Safety: The English family, especially Rikki-tikki-tavi the mongoose, are a threat to Nag and Nagaina's survival. Rikki-tikki-tavi is a natural predator of snakes and poses a constant danger to them and their eggs.
They see the English family as an obstacle to their own survival and a reminder of their past loss. Their desire to eliminate the family is born from a combination of anger, fear, and the instinct to protect themselves and their offspring.