As the preeminent god of the R̥gveda, Indra has a variety of roles. But first of all Indra is a warrior, upon whom depend the protection and prosperity of his worshipers. His weapon is the vájra, the mace. In later tradition, when Indra was reduced to a storm god, the vajra became a thunderbolt. But in the R̥gveda it was a weapon, which could be thrown at an enemy or smashed down upon him, and the principal means by which Indra asserted his power.
Vr̥tra
The foremost story of Indra in the R̥gveda is the narrative of the battle between Indra and Vr̥tra. Vr̥tra was a gigantic cobra, who was twisted around a mountain that enclosed the waters. In order for life to exist Vr̥tra had to be destroyed. Indra battled the serpent, alone, according to some hymns, or with the help of the Maruts or other gods, according to others. After a furious battle Indra killed Vr̥tra with his mace and smashed open the mountain, releasing the waters. This myth is occasionally merged with others, so that not only the waters but also the cattle and the sun emerge from the mountain. The name Vr̥tra means “obstacle,” and one of the char acteristic epithets of Indra is vr̥trahán, which can mean either “smasher of Vr̥tra” or “smasher of obstacles.” There is little difference between these two interpretations, however, since Vr̥tra is the paradigm of all obstacles. To evoke Indra as the smasher of Vr̥tra, therefore, is to evoke him as the god who smashes all obstacles.
The narrative of the destruction of Vr̥tra is associated particularly with the midday soma-pressing, which is dedicated to Indra alone or to Indra and the Maruts.
Vala
The Vala myth is the second great narrative of Indra and a complement to the Vr̥tra story. According to this myth a group called the Paṇis captured the cattle and kept them trapped in the Vala cave. Indra opened the Vala cave and released the cattle and the dawns. Remarkable in this story is that Indra does not release the cattle using his mace as his weapon, but rather using the power of the truth in the songs he chants. Accompanying him and joining him in his chant are groups of priests, the Aṅgirases, sometimes along with the Navagvas or the Daśagvas. In this narrative, therefore, Indra is a priest-king rather than a warrior-king as he is in the Vr̥tra myth. In his role as priest-king Indra is also called bŕ̥haspáti, the “lord of the sacred formulation.” Br̥haspati appears not only as Indra, but also as a separate divinity alongside Indra. Gradually, as Indra and the Vedic king, who personifies Indra, progressively lose their priestly functions in the late R̥gveda and in the later Vedic tradition, Br̥haspati increasingly stands apart from Indra. As the Vr̥tra story is connected with the Midday Pressing, so the Vala story was associated with the Morning Pressing, which takes place with the appearance of dawn.+++(5)+++ In the R̥gvedic period the dakṣiṇā, the reward of cattle to the priests, was also given at the Morning Pressing. The cattle that come to the priests thus reflect the advent of the cattle and dawns in the world.+++(4)+++
Although the two major mythological narratives with Indra as protagonist are the Vr̥tra and the Vala victories, he figures in many other episodes—too many to mention here—which are often fragmentarily attested and poorly understood.
Parents
We may start with his parentage. Although the identity of Indra’s mother is not clear, in the occasional mentions of her she is a vivid character—as in the snatches of dialogue between him and his mother in the famous birth hymn IV.18, where she tries to persuade him not to pursue an unnatural exit from her womb. Elsewhere she offers him soma to drink directly after his birth, soma that he stole from his father, named as Tvaṣṭar (III.48; also IV.18.3). And in an even more enigmatic snatch of dialogue (VIII.45.4–6 ≅ VIII.77.1–2) she seems to reassure the just-born Indra that he will ultimately prevail. As just noted, Indra seems to participate in a rivalry with his father, who may be Tvaṣṭar. The unnatural birth and the rivalry with the divine father are of course well-nigh universal attributes of “the hero”; the many prodigious feats attributed to Indra just after his birth are also typical of heroic biography.
Indra vs Sun and Dawn
Two minor but intriguing myths pit Indra against the two most important forms of celestial light, the Sun and Dawn. We find the merest allusions (primarily IV.30.8–11) to a puzzling episode in which Indra crushes the cart of Dawn and she runs away.+++(4)+++ Alluded to just a bit more (primarily V.29.5, 9–10; V.31.11; I.121.13) is the chariot race in which Indra bests the chariot of the Sun, apparently by tearing the wheel off his chariot. This latter myth is somehow connected with one that is better attested, though hardly better understood, in which Indra and a sidekick Kutsa drive on the same chariot, drawn by the horses of the Wind, to the house of Uśanā Kāvya (a name with a shadowy attestation also in Avestan mythology), to receive some aid or advice, preliminary to slaying Śuṣṇa, the often-mentioned opponent of Kutsa.
Emuṣa
Indra has a number of other named adversaries. In one striking whiff of a narrative, Indra, aided by Viṣṇu in some versions, shoots a boar named Emuṣa, enabling him to acquire a special mess of rice porridge hidden in or behind a mountain (see esp. VIII.77; also VIII.69.14–15, I.61.7). This myth is further developed in Vedic prose.
Namuci
Another myth with more presence in later texts involves Indra’s slaying of Namuci by beheading him (e.g., V.30.7–8). In the later versions Indra accomplishes this by trickery, and part of the trick (using the foam of the waters as weapon) is already mentioned once in the R̥gveda (VIII.14.13).
Other victims
The names of other victims of Indra include Śambara, Pipru, Dhuni and Cumuri, and Varcin, inter alia. The details of these battles are too sketchy to provide much in the way of narrative mythology.
Fallow bays
Like a number of other gods, Indra has his characteristic draft-animals, and his are especially prominently featured in the text. His pair of fallow bays (hárī) conveys him everywhere, especially to and from the sacrifice. They have their own food offered to them at the sacrifice (roasted grain, see, e.g., III.35), and hymns were even devoted to a libation made when the pair was hitched up for the return journey after the sacrifice (see I.61–63). The mention of the fallow bays is sufficient to signal that Indra is present in the context, and hárivant “possessing the fallow bays” is a standing epithet of Indra.