a viper in (one's) bosom

A friend, lover, or relation who proves to be traitorous, untrustworthy, deceitful, or ungrateful. (Used especially in the phrase "nourish/nurse/nurture a viper in one's bosom.") Well, it turns out that Margaret was quite a viper in my bosom. I put my neck on the line to get her a job in our company, and then she turns around and tries to steal my position! I thought our love was not only mutual but indestructible; and yet, I have nursed a viper in my bosom all these years: my darling husband has cast me out and run off with a younger woman. I thought the profligate had seen the light and was seeking redemption, and so I took him into my care. But before long, I knew I had nurtured a viper in my bosom, as I awoke one morning to find myself robbed blind!

nourish a viper in (one's) bosom

To befriend, look after, or take care of someone who proves to be traitorous, untrustworthy, deceitful, or ungrateful. I thought the profligate had seen the light and was seeking redemption, and so I took him into my care. But before long, I knew I had nourished a viper in my bosom, as I awoke one morning to find myself robbed blind! I thought our love was not only mutual but indestructible; and yet, I have nourished a viper in my bosom all these years: my darling husband has cast me out and run off with a younger woman.

nurse a viper in (one's) bosom

To befriend, look after, or take care of someone who proves to be traitorous, untrustworthy, deceitful, or ungrateful. I thought the profligate had seen the light and was seeking redemption, and so I took him into my care. But before long, I knew I had nursed a viper in my bosom, as I awoke one morning to find myself robbed blind! I thought our love was not only mutual but indestructible; and yet, I have nursed a viper in my bosom all these years: my darling husband has cast me out and run off with a younger woman.

nurture a viper in (one's) bosom

To befriend, look after, or take care of someone who proves to be traitorous, untrustworthy, deceitful, or ungrateful. I thought the profligate had seen the light and was seeking redemption, and so I took him into my care. But before long, I knew I had nurtured a viper in my bosom, as I awoke one morning to find myself robbed blind! I thought our love was not only mutual but indestructible; and yet, I have nurtured a viper in my bosom all these years: my darling husband has cast me out and run off with a younger woman.

viper in one's bosom

Also, snake in one's bosom. An ungrateful or treacherous friend, as in I got him dozens of freelance jobs, and then he told everyone I was a lousy musician-nothing like nourishing a viper in one's bosom . This metaphoric expression, often put as nourish a viper (or snake) in one's bosom, comes from Aesop's fable about a farmer who shelters a snake dying from the cold, which then fatally bites him after it recovers. It was referred to by Chaucer and Shakespeare, and appeared in numerous proverb collections.

a viper in your bosom

a person you have helped but who behaves treacherously towards you.

The phrase comes from one of Aesop's fables, in which a viper reared in a person's bosom eventually bites its nurturer. The idea is also found in Latin (in sinu viperam habere ) and the expression appears in various forms in English from the late 16th century.

viper in one's bosom, (nourish) a

An ungrateful and treacherous friend; an individual whom one has helped and who returns the favor with treachery. This term comes from Aesop’s fable about a peasant who brings indoors a snake dying from the cold and is fatally bitten as soon as the snake recovers. Chaucer was among the first of the many writers to use this metaphor, which also made its way into the proverb collections of John Ray (1670), James Kelly (1721), and Thomas Fuller (1732). The term is variously put as snake or viper.