Aryaman (अर्यमन्, pronounced as "aryaman"; nominative singular is aryama) is one of the early Vedic deities. His name signifies "bosom friend", "play-fellow" or "companion". He is the third son of Aditi. He is an Aditya. He is supposed to be the chief of the manes and the Milky Way (aryamṇáḥ pánthāḥ) is supposed to be his path. He was commonly invoked together with the deities Varuṇa and Mitra, also with Bhaga, Bṛhaspati, and others. In the Ṛgveda there are two major groups of gods, the Devas and the Asuras. Unlike in later Vedic texts and in Hinduism, the Asuras are not yet demonized. Aryaman in Ṛgveda is an Asura, Mitra and Varuna being their most prominent members. Aditi is the mother of Adityas, led by Varuna and Mitra.
The Hindu marriage oaths are administered with an invocation to Aryaman being the witness to the event.
Similarity with other Indo-European divinities
The vedic Aryaman and the zoroastrian Airyaman, who in the Avesta is the Yazata of friendship and healing, is the same being. In old German or Saxon mythology, Irmin was the god of war and storms. Often identified with Norse Odin and closely related to him, Irmin is derived from Vedic god Aryaman. Germans considered Milky Way to be the path of Irmin, and called it 'Irmin's Way'.
^Gerald James Larson (editor). Myth and Indo-European Antiquity. University of California Press, 1974. ISBN9780520023789. ... This protector in Indic tradition was Mitra, and Mitra's helper was Aryaman. In Germanic tradition the god cognate to Aryaman was Irmin. And Irmin has been interpreted as being none other than Tyr himself ...