सुब्रह्मण्याह्वानम्
शातपथजैमिनीयब्राह्मणयोः, तैत्तिरीयारण्यके च।
सौरार्थः
कुमारीलः -
एवं समस्त-तेजाः परमैश्वर्य-निमित्तेन्द्र-शब्द-वाच्यः सवितैवाहनि लीयमानतया
रात्रेर् अहल्या-शब्द-वाच्यायाः क्षयात्मक-जरण-हेतुत्वाज्
जीर्यत्य् अस्माद् अनेनैवोदितेनेत्य् आदित्य एव अहल्याजार
इत्य् उच्यते न तु परस्त्री-व्यभिचारात्।
the argument of Ahalya as the night from “अहनि लीयमाना” and Indra as the sun, the destroyer of the night, occurs after he says “यथा वा न विरुद्धत्वं तथा तद्गमयिष्यति,” so his intent there is to interpret in a way that is in line with शिष्टाचार.
उषसो जारः
Source: TW
Agni is invited in a variant of subrahmanya vachana in agniShTut. He’s called ushaso jāra…
agna āgaccha rohitava āgaccha, bharadvājasya aja, sahasassūno, vārāvaskandin uşaso jāra, āngirasa brāhmaņa āngirasa bruvāņa.
But गौतमीयनिगदः of Angishtut is meant to be different I think and not just a variant to Agni, since इन्द्रागच्छ/आगच्छ मघवन्, etc. is uttered by the Subrahmanya after atithyeshti as per the same Latyayana Shrauta Sutram alongside anvarambhana/touching of the Yajamana and wife.
Also refer jaiminiya brahmana 2.78,79,80. JB notes in passing that subrahmanya call in agniShTut is all AgneyI, in indrastoma is all aindri and vaishvadevI for all Gods but disagrees.
Indra fertility
Source: dhvasra nikhil
Even being the lover of a married woman is not problematic because we are talking about literal Gods here, forces of nature. Thus we have Vedic references to Índra giving children to the wife of an impotent man (R̥V 1.116.13, 1.117.24, 10.39.7)—though one could choose to interpret this as literally “giving” (√dā) a son without an implication of being a lover, if one wishes.
Adding to this, remember that the most “sexually puritan” religion in the world, Christianity, has their god imprægnating a married woman. Clearly there is no religion aside from ʾIslām that sees gods’ relationships with women the same as mens'.
In any case the word used with Áhalyā in the Brā́hmaṇa-s is jārá “lover” (not necessarily extramarital by the definition of the word—it could theoretically refer to a husband—but in this case necessarily extramarital since Áhalyā Māítrēyī is a human woman and nowhere mentioned to be His wife).
I don’t see anything problematic about either case; in the first, a God is doing a favor to a family by providing them with offspring, and in the second, a virile God is the lover of a human maiden with no mention of deceit by Índra or adultery by Áhalyā. There is no falsehood or transgression of moral law involved.
वाल्मीकीये
It sort of “euhemeristic” attempt on vAlmIki’s part to interpret the 3 vaidika subrahmaNya mantra-s: ahalyAyai jAra | kaushika brAhmaNa | gautama bruvANa | vAlmIki did not merge the gautama bruvANa part into the story and stuck with ahalyAyai jAra. But he brings in kaushika brAhmaNa as the vishvAmitra character in the tale. - MT