To win someone over or to tame (another's heart); a transitive form meaning to make someone or an animal become attached or accustomed.
彼は何年もかけて野生の馬を懐けた。
He spent years taming (winning over) the wild horse.
子どもたちに懐けるのが上手で、すぐに人気者になる。
He's good at winning kids over and quickly becomes popular.
新しいペットを懐けるには根気が必要だ。
It takes patience to get a new pet to warm up to you.