The female viper conceives by taking the male's head in her mouth. She then bites off his head and he dies. When the young are ready to be born, they bite through their mother's side, and she dies.

Pierre de Beauvais says that the viper will flee from a naked man but attack one who is clothed, a behavior normally attributed to the snake in general.

The Y version of the Physiologus says that the male viper resembles a man, and the female resembles a woman to the waist, but below the waist she has a crocodile's tail; this is the reason the female must conceive through the mouth, and also why the young must come out through her side.

The Aberdeen Bestiary adds a peculiar twist to the story, in order to use it for the basis of a sermon. Quoting Ambrose, it says of the viper: "When it feels the desire for intercourse, it goes in search of a lamprey [muraena] already known to it or prepares to copulate with a new partner. It goes to the shore and makes its presence known with a hiss, inviting her to its conjugal embrace. The lamprey, once invited, does not demur and shares with the poisonous snake the union it seeks." Cambridge University Library, MS Ii. 4. 26 also has this story.

The Aberdeen Bestiary uses the story of the male viper mating with a female lamprey for a long sermon on conjugal rights. It urges women to "put up with the behavior" of their men: "Let him be harsh, deceitful, uncouth, unreliable, drunken: are any of these things worse than the poison from which the lamprey, in intercourse, does not shrink? When she is invited, she is not found wanting and embraces the slimy snake with sincere affection. The man puts up with your mischief and your feminine tendency towards triviality. Can you, o woman, not stand by your man?" The man also gets a lesson: "But you too, O man, for we can also bring you into the discussion, set aside the passion in your heart and the roughness of your manner when your loving wife comes to meet you, get rid of your ill-humor when your wife sweetly rouses you to express your love. You are not her master but her husband; you have gained not a maidservant but a wife. God wished you to govern the weaker sex, not rule it absolutely. Return her care with attention; return her love with grace. The viper pours out its poison; can you not get rid of your harsh attitude?"

Hildegard von Bingen says, "If anyone finds a dead viper in an area where vipers live (since it is impossible to get a live one), he should burn a great fire, with strong wood, in a secret place, and throw the viper in. He should hurriedly leave that place, lest the poison or bad vapors touch him. After it has been reduced to ashes, the person should leave any part of it that remains, but he should take its ashes, and the ashes of the charcoals in which it was burned, and keep them in a linen cloth. Then, if someone swells up on some part of his body, he should place that cloth, with the ashes, over the swelling. The swelling will immediately go away." (Throop translation)