snake in one's bosom
书面·形容身边隐藏的背叛者
例句
I trusted her, but she turned out to be a snake in my bosom.
典故来源
源自《伊索寓言》，农夫将冻僵的蛇放在怀中取暖，蛇苏醒后反咬农夫，比喻恩将仇报。