I've come across the expression 懐に入れた人間 a couple of times in texts describing (male) characters, e.g. 一度懐に入れた人間はとことん甘やかしてしまう, but I don't quite understand what it means. "Once he thinks dearly of someone, he will pamper that person a lot"?
To expand on Yuuichi Tam's answer, the 懐【ふところ】 is the pouch-y part of a kimono where the left and right sides of the robe overlap, and this area tends to pouch out a bit over the obi. This is where folks would traditionally keep a billfold, for example. This is pretty close to the middle of one's chest, and thus one's heart, so 懐【ふところ】に入【い】れる became a metaphor for "to let [someone] into one's heart" → "to think dearly and fondly about someone".