Atri's trajectory across Hindu religious history illustrates a broader pattern common to several Rig Vedic family patriarchs: a figure who within the Rig Veda itself is known chiefly as the name attached to a body of ritual hymns grows, across the many centuries of later epic and Puranic literature, into an elaborately storied sage with a wife, named Anasuya, celebrated for extraordinary chastity and virtue, sons identified with major later deities in some traditions, and a body of miracle narratives, including the fire ordeal, that have no direct counterpart in the Vedic hymns bearing his family name.
Modern philology treats this gap cautiously, generally declining to read the later legendary material back into the Rig Veda's own much sparer, ritually focused hymns, and instead studying the family book on its own terms as sacrificial poetry addressed to specific deities for specific ritual occasions rather than as biography of its named author.
Within the Hindu tradition itself, the relationship runs the other way: Atri's later stature as a great sage is understood to flow naturally from, and to confirm the greatness of, the Vedic revelation his family transmitted, so that the later legendary elaboration is read as making explicit a sanctity the ancient hymns already carried rather than as a separate, later invention layered on top of them.