Just after uttering the beatific words in Mahābhārata, the greatest narrator of Mahābhārata, Ugraśravā himself gets introduced to his infinitie number of readers– in the beginning of Mahābhārata, it is said that the ̎Paurāṇika̍ Ugraśravā, son of Sūta Lomaharṣaṇa has come to the hermitage of Śaunaka–
lomaharṣanaputra ugraśravāḥ sautiḥ paurāṇiko naimiṣāraṇye.
In ancient society, hermits and sages showed enough respect to the Sūta(s), because was their their knowledge was like that of well-versed Brāhmaṇa(s) and Kṣatriya(s), according to Purāṇa(s)– ̍amalaprajñā̍. If we consider, according to the dictum of Manu, the ̍Sūta̍ race that was born out of the union between a Kṣatriya man and a Brāhmaṇa woman, came to be known as ̍Aitihāsika̍ (historical̍) and ̍Paurāṇika̍ (mythological), even then it is to be said that, in the great task of narrating the histories of the sages and kings, especially such a grand tale as of Mahābhārata, along with its many incorporations and retellings over the ages– people of this ̍hybrid̍ race was considered to be the most suitable.

During the twelve years of continuing yajña-performance, one Paurāṇika has come to the hermitage of Śaunaka, in Naimiṣāraṇya, and he is not just a narrator, he is the best of Paurāṇika(s), the knowers of mythologies, he is the son of Romaharṣaṇa. There was no second narrator hike him. He was inferior to the Brāhmaṇa(s), in terms of the caste hierarchy, because his mother was of a Brāhmaṇa family, and father, a Kṣatriya. In the first letter of Romaharṣaṇa, ̍la̍ and ̍ra̍ are inseparable. Everybody has forgotten what had been his original name, so interesting was his art of storytelling, the the hairs in the body of every listener got excited in happiness. So his name became ̍Lomaharṣṇa̍–
lomāni harṣayañcakre śrotṛṇāṃ yaḥ subhāṣitaiḥ. He was a favourite disciple of Vyāsa himself.

Now the son of that Lomaharṣaṇa has come to the hermitage of Śaunaka. He also has the ability to excite the hairs of his listeners. His reputation (śravas) in storytelling has gone very high, so his name is Lomaharṣaṇi Ugraśravā. He is a Sūta̍s son, so he is Sauti.

Actually, there was a special position for the Sūta(s), in the age of Mahābhārata and Purāṇa(s), they were a class by themselves. In Purāṇa(s) it is shown that from the day we got the first king of this earth, we have also the emergence of the ̍Sūta̍. According to Purāṇa, the first ̍proper̍ king was Pṛthu. When Pṛthu was born, that very day Pitāmaha Brahmā created the Sūta(s) and Māgadha(s), out of the soil of yajña-offerings. The sages and hermits assembled there, asked the Sūta and Māgadha(s) to sing the praise of the great Pṛthu.

Since the day when the Sūta(s) and Māgadha(s) sang the praise of Pṛthu, they came to be known as the minstrels of great dynasties. The glories and deeds of the great dynasties, the glorious ascetic feats achieved by sages– all these they held in their memories, so the Sūta(s) were the historians and mythologists of those days, which was called ̍Paurāṇika̍ —
sūtaḥ paurāṇikāḥ proktāḥ.

The Sūta(s) were believed to be the first hybrid race of India. It is said that in a Yajña performed by Pṛthu, who gave his name to this Pṛthivī (Prithivi, Earth), the āhuti (ahuti; offering) prepared for Vṛhaspati, guru of the gods, got merged with the offering dedicated to Indra. With the offering for Vṛhaspati in hand, the mantra was uttered for Indra. Indra, as the king of gods, is a Kṣatriya. Thus, from the merging of havi(ghee), emerged the hybrid race, the first on earth–
sūtyāyāmabhavat sūtaḥ prathamaṃ varṇavaikṛtam.
Perhaps that is why, Mahābhārata was originally composed by a great Brāhmaṇa like Vyāsa, and uttered by another Brāhmaṇa like Vaiśmpāyana , but the narrator, from whose lips we first get to learn the story, is a poet of a hybrid origin.

Janamejaya started the Sarpayajña in order to avenge the death of his father. Mahābhārata starts with that Sarpayajña. Sage Āstīka stopped the yajña, and the storytelling began. All the sages from all kingdoms were assembled there. The great sage Vyāsa was also present. Vyāsa̍s own blood was flowing in the lineage of Kuru and Pāṇḍava(s), so he had a special affection for them. After the death of Dhṛtarāṣṭra in Vānaprastha, and the Mahāprasthāna, he started writing Mahābhārata– the previous history and the future of them. He might not have ̍written̍ it by hand, but it took him three years to conceptualise the whole thing–
tribhivarṣairmahābhāgaḥ kṛṣṇadvaipāyano̍vravīt.
Ugraśravā Sauti was narrating Mahābhārata, sitting in Naimiṣāraṇya. Here, he is the speaker. But he had been among the listeners in the court of Janamejaya. There, Vaiśampāyana, disciple of Vyāsa, was the speaker. In Ādiparva of Mahābhārata, it is said that Vyāsa initially composed only Jayasaṃhitā, which only related the battle between the Kaurava(s). Then Vaiśampāyana added the portion beginning with the birth of the Kuru-Pāṇḍava and other things, which became Bhāratasaṃhitā. It was that larger version of Bhāratasaṃhitā which Vaiśampāyana narrated Mahābhārata, then, adding more legends and sub-plot stories, Ugraśravā narrated it to the the sages of Naimiṣāraṇya. In this regard, Ugraśravā Sauti is the creator of the third version of Mahābhārata.

The moment Ugraśravā Sauti has started telling the story, he knew that it was formerly told by so many poets  earlier. His predecessors might have heard this from their predecessors, in a different way, and they might have described it in their own ways–

vyācakhyuḥ kavayaḥ kecit.
He knew that the story of Mahābhārta was as dynamic and vast as Bhārata itself, it is also the representation of a human race so various , so dynamic. He also knew that the so-called Aryan community of India had not been able to maintain the ‘purity’ of blood. Thoughts and ideas of hundreds of poets have been assimilated here, sometimes raw interpolations have also come in. The history of a grand nation cannot be conceptualised in the mind of a single poet. Whatever influences have come upon the mind of the nation, the poets have captured it from time to time, in the panorama of epical history.In the very beginning of Bhārata-kathā, he says — “I am not the only one person who narrates it first. Poets have narrated it before me, and afterwards, other poets will do so–
ākhyāsyanti tathaivānye itihāsamimaṃ bhuvi.
Since he was of a hybrid origin, the responsibility of telling dynamic and hybrid narration of dharma-artha-kāma-mokṣa falls on this Sūta. Because he was of a hybrid origin, for him, the interpolations by so many poets over the years were not ‘untoucahbale̍’, he could assimilate all of them.This Sūta has a fondness for the the information, all the incorporations and stranger-details in Mahābhārata. And he has equal regard for those who have told the story of Mahābhārata before him, and sympathy for those who were narrating it in his own time, and he has good wishes for those who will narrate this story with due respect in future–
ākhyāsyanti tathaivānye itihāsamimaṃ bhuvi.

Perhaps for this reason, Ugraśravā Sauti is the narrator of so many Purāṇa(s). Bhāgavata purāṇa, Harivaṃś purāṇ and Padmapurāṇa are narrated by Sauti.