In the middle Vedic period, Viṣṇu became a central figure as the embodiment of the sacrifice itself+++(4)+++ and therefore of a power that can exceed even the might of the gods. In classical India, of course, he finds an even greater destiny.
There is little sign of those futures of Viṣṇu in the R̥gveda, since it has only a half dozen hymns dedicated to Viṣṇu or to Indra and Viṣṇu (I.154, 155, 156; VI.69; VII.99, 100).
Strides
Viṣṇu appears alongside Indra fairly often, especially in his battle with Vr̥tra (IV.18.11, VI.20.2, VIII.100.12), and he is also Indra’s partner and ally generally. The only acts that are especially his are his three strides or three steps. With these strides Viṣṇu encompasses the earth, and with his third step he disappears into a realm where none can follow (I.155.4–5). Or he enters into heaven where there is the “wellspring of honey,” the source of soma (I.154.5), or the highest cattle-pen (III.55.10).
He is therefore the god who is wide-ranging (urugāyá) and wide-striding (urukramá). The purpose of his strides is to create space and a place for people to live and move (I.155.4, VI.49.13, VII.100.4).
This purpose could explain Viṣṇu’s close connection with Indra in the fight with Vr̥tra, since Vr̥tra represents what confines and hinders, and Viṣṇu’s strides what opens and frees. The strides of Viṣṇu in the R̥gveda anticipate the strides that Viṣṇu takes as Vāmana, the dwarf avatar of classical Hinduism, and also in the middle Vedic literature Viṣṇu as the sacrifice is a dwarf (ŚB I.2.5.5). However, there is no direct evidence that Viṣṇu already has the form of a dwarf in the R̥gveda.