From Slavic Folklore
A girl once fell in love with a snake, and loved him alone. And he carried her off to his estate. In his dwelling house were beautiful drinking cups all of crystal, for his dwelling place was underground in a sort of grave. Well, you must know, his old mother at first lived with them. How could she do otherwise?
Well, the girl, whether she lay with the snake or not I cannot say, became enceinte, and in due course of time bore twins – one a boy and one a girl – and like their mother as wax is to wax. And she, too, was as beautiful as a floweret. Well, God having given her these children, she said:
“Look, you! As they have been born in human guise, let them also be christened in human wise.”
She seated herself in a golden carriage, took the children on her knee, and drove home to her native village to the priest. The carriage did not drive through the field, and yet the mother knew what was happening. The old woman raised a hue and cry in the whole village, seized a sickle, and hie! Away into the field. The daughter, seeing their fate sealed, called to the children and said:
“Fly away, my children, into the world as birds; you, my little son, as a nightingale; you, my little daughter, as a cuckoo.”
The little nightingale flew out of the right, the cuckoo out of the left, window of the carriage; and the carriage horses and all the rest – nobody knows what became of them. The mother had disappeared, too; only by the roadside grew a dense thicket.
Source:
Russian and Bulgarian Folk-Lore Stories, A.W. Strickland, 1907
Kotharian Lightning 