In this chapter of the Shankhayana Grihya Sutras, a text associated with the Rig Veda, part of the Hindu marriage ceremony is described. In preparing the bride for the marriage, the bride's family priest does the following:
Then (the Âkârya of the bride's family) makes the girl sit down behind the fire, and while she takes hold of him he sacrifices with the Mahâvyâhritis, and then he makes Âgya oblations to Agni, to Soma, to Pragâpati, to Mitra, to Varuna, to Indra, to Indrânî, to the Gandharva, to Bhaga, to Pûshan, to Tvashtar, to Brihaspati, to the king Pratyânîka.
After they have regaled four or eight women, who are not widows, with lumps of vegetables, Surâ, and food, these should perform a dance four times.
The same deities (they worship also) on behalf of the man,
And Vaisravana and Îsâna.
Most of these gods are recognizable: Soma is Chandra the moon god, Indrani is Indra's wife Shachi, Tvashta is Vishwakarma the divine architect, Vaishravana is Kubera god of wealth, Ishana is Shiva, etc.
But my question is, who is "king Pratyanika" that the priest gives an offering to? I assume he's a Vedic god, like the others, but as far as I can tell there are no Vedic hymns addressed to him; see the Rig Veda Anukramani in my answer here. Does he have another name? The Sanskrit word pratyanika means enemy or hostility, so perhaps he's some sort of god of enmity.
If it helps, the ritual this is part of is called the "Indranikarman", as Indrani or Shachi is worshipped in it. Has anyone heard of worshipping Pratyanika in the Indranikarman ritual?