Indra, in the Subramanaya invocation is referred to as both Kaushik, one who calls him Gautama as well as the lover of Ahalya (Shatpatha Brahman relevant chapter). While the part about Gautam and Ahalya seems straightforward since Indra impersonated the rishi, how does Kaushik fit in?
3:3:4:18. 'Come, O Indra!' Indra is the deity of the sacrifice: therefore he says, 'Come, O Indra!' 'Come, O lord of the bay steeds! Ram of Medhâtithi! Wife of Vrishanasva! Bestriding buffalo! Lover of Ahalyâ!' Thereby he wishes him joy in those affairs of his.
3:3:4:19. 'O Kausika, Brahman, thou who callest thee Gautama.' Just so has this (formula) been devised in these days by Âruni, to wit, 'thou who callest thee Gautama:' he may say it, if he choose, and if he does not choose, he need not attend to it . 'In so and so many days, to the Soma-feast,' (stating) in how many days from hence the pressing is to be.
According to Sâyana's commentary, the king Kusika desired to have a son equal to Indra, so the latter was born as Kusika's son Gâthin (Gâdhin). This is corroborated by the RV Verse 1.10.11 as well:
11 O Indra, Son of Kuśika, drink our libation with delight. Prolong our life anew, and cause the seer to win a thousand gifts.
Does it imply in any way that Indra, as Gadhi, was married to Ahalya?