confidante闺蜜/红颜知己(女性);
intimate至交;
mentor导师;
sworn brother结拜兄弟;
superior/boss上司/老板;
partner搭档;
couple情侣;
companion同伴;
penpal笔友;
comrade-in-arms战友;
fellow-apprentice师兄弟;
bosom friend知心朋友