To become attached to or affectionate toward someone; to grow fond of or tame (as an animal becoming accustomed to a person).
子猫がすぐに私になついてくれてうれしい。
I'm happy the kitten became attached to me right away.
新しい先生になかなかなつかなかった子どもが、少しずつ心を開いた。
The child who didn't warm to the new teacher at first gradually opened up.
野生のキツネをなつかせるのは簡単ではない。
It's not easy to tame a wild fox.