Rikki-tikki is always described as curious, and almost impossible to frighten.
A mongoose by its very nature seems to be a curious creature. When Rikki-tikki first washes up on the family’s doorstep, he shows that he is curious rather than afraid.
It is the hardest thing in the world to frighten a mongoose, because he is eaten up from nose to tail with curiosity. The motto of all the mongoose family is ``Run and find out''; and Rikki-tikki was a true mongoose.
Rikki-tikki decides that he wants to be a house mongoose, like his mother before him. He makes a home with the people, and you can tell by his behavior with them that he is curious about everything around him. On his first day he “spent all that day roaming over the house” checking to see what he could eat and what he couldn’t, and just looking around in general, and at night was too curious about the house to sleep.
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; but he was a restless companion, because he had to get up and attend to every noise all through the night, and find out what made it.
Rikki-tikki’s curiosity saves his life when it comes to snakes in the yard. He takes nothing for granted. He learns right away that there are two killers, the cobras, and he knows that he will need to fight them. He is also aware that there are other snakes, and it does not take him long to kill little Karait.
Rikki’s curiosity is a survival trait. It is what keeps him on his toes, and allows him to stay one step ahead of the snakes and other predators. It also allows him to protect the family, which he considers his job as a house mongoose.