Indra asks all the deities to support him and call to him. They agree and run forward to the kill. Vritra sees them and decides to terrify them; he breathes out, and before his snorting all the gods run away. Only the Maruts do not abandon Indra; they tell him to smite and show his strength. Indra recognises them as his friends and gives them a share in the midday litany, which until then was his alone. The Brahmana quotes the Rigveda verse: all the gods fled Vritra's snort; let Indra's friendship be with the Maruts. The hymn adds that thrice sixty Maruts were with him and that their host is a sharpened weapon.
While Indra strives to smite Vritra, the Maruts have withdrawn and stand on an ashvattha tree. He calls them to be his force; they ask what they will get. He draws two cups of Soma. They join him but first put their vigour aside with one cup; he asks for their vigour and must draw a third cup, after which they join in earnest and he conquers. The text reads Indra as the nobility and the Maruts as the people, says he feared their desertion, and adds the Mahendra cup for Indra become great. Elsewhere (2.5.3) the Maruts scorch Vritra at midday and sport around Indra singing his praises.
What is different here:
The Maruts hold back and bargain for three cups instead of staying out of loyalty; no flight of the other gods; an explicit political reading (ruler and people).
The Rigveda also holds the opposite memory. In 1.165.6 Indra asks the Maruts where their nature was when they left him alone to slay the dragon, and 8.7.31 asks them what friend they still have since they left Indra all alone. Yet the same hymn 8.7 says they tore Vritra limb from limb and helped Indra in battle.
What is different here:
The Maruts are accused of deserting Indra; the hymns keep both accounts without reconciling them.
Sources: Rigveda Brahmanas: the Aitareya and Kausitaki Brahmanas, tr. A. B. Keith (1920); Hymns of the Rigveda, tr. R. T. H. Griffith (1896), hymns read for the Vedic layer; The Satapatha-Brahmana, tr. Julius Eggeling (Sacred Books of the East 12, 41)