Nag knew that too and, at the bottom of his cold heart, he was afraid.
Nag was thinking to himself, and watching the least little movement in the grass behind Rikki-tikki.
He jumped up in the air as high as he could go, and just under him whizzed by the head of Nagaina, Nag's wicked wife.
"Wicked, wicked Darzee!" said Nag, lashing up as high as he could reach toward the nest in the thorn-bush.
But Nag and Nagaina had disappeared into the grass.
If Rikki-tikki had only known, he was doing a much more dangerous thing than fighting Nag, for Karait is so small, and can turn so quickly, that unless Rikki bit him close to the back of the head, he would get the return stroke in his eye or his lip.
But he remembered Nag and Nagaina, and though it was very pleasant to be patted and petted by Teddy's mother, and to sit on Teddy's shoulder, his eyes would get red from time to time, and he would go off into his long war cry of "Rikk-tikk-tikki-tikki-tchk!"
"And how am I to be sure that Nag won't mistake me for you some dark night?"
"But Nag is in the garden, and I know you don't go there."
"That's Nag or Nagaina," he said to himself, "and he is crawling into the bath-room sluice.
At the bottom of the smooth plaster wall there was a brick pulled out to make a sluice for the bath water, and as Rikki-tikki stole in by the masonry curb where the bath is put, he heard Nag and Nagaina whispering together outside in the moonlight.
"But are you sure that there is anything to be gained by killing the people?" said Nag.