Shesha, the first born of Kadru's thousand sons, will not live with his brothers, who envy Vinata's son and wish harm. He goes away and does austerities on air alone at Gandhamadana, Badari, Gokarna and the Pushkara woods, until his body is skin and sinew. Brahma comes and asks what he wants; Shesha asks only that his heart delight in virtue. Brahma grants it, and asks him a favour: hold the earth, which shakes with her mountains and forests. Shesha says, place her on my head, and goes through a hole into the depths and bears her from below. Brahma calls him Dharma and gives him Garuda as a friend.
Mahabharata, Adi Parva, tr. K. M. Ganguli (Project Gutenberg 15474)
At the end of the Yadavas Krishna finds his brother Balarama sitting in yoga under a tree. From his mouth a great white serpent with a thousand heads comes out and goes away into the ocean, where the nagas Vasuki, Takshaka and Karkotaka come to receive him. So the epic tells, without saying so, that the brother was Shesha all along.
Mahabharata, Ashvamedhika and Mausala Parvas, tr. K. M. Ganguli (Project Gutenberg 15477); Shesha (Wikipedia)
Sources: Mahabharata, Adi Parva, tr. K. M. Ganguli (Project Gutenberg 15474); Mahabharata, Ashvamedhika and Mausala Parvas, tr. K. M. Ganguli (Project Gutenberg 15477); Shesha (Wikipedia)
During the dissolution Vishnu lies on the serpent Ananta in the cosmic waters.
Two demons born from Vishnu's ear-wax threaten Brahma and steal the Vedas; who saves the day depends on the sect — Vishnu as Hayagriva in the epic line, or the Goddess who must first leave Vishnu's body in the Devi Mahatmya.
The cosmic person of the Purusha Sukta and the Narayana who rests on the waters are fused into Vishnu's cosmic identity, pictured as Anantashayana.
The Wind and the serpent test their strength on a mountain; the broken pieces become holy hills of the south and the island of Lanka.
A potter's boy of Pratishthana, son of a serpent king and a Brahmin woman, judges the other children so fairly that Vikramaditya of Ujjain marches on the town; he shapes soldiers, horses and elephants of clay, nectar from the serpents wakes them, and they win. The town raises flags for his return, the gudi, and his era, the Shalivahana Shaka, begins.
Kashmir was the lake Satisara, and the demon Jalodbhava in it could not be killed in water. Kashyapa brings the gods to Naubandhana; Ananta splits the mountain with his plough, the lake drains, and Vishnu takes the demon's head with the discus. Srinagar's tradition adds that the Goddess, as a myna, dropped a pebble from Sumeru on the demon that grew into Hari Parbat, and Navreh is the day she settled there.
Warned that Devaki's eighth child will kill him, Kamsa imprisons her and Vasudeva and kills their sons. The eighth is born at midnight; the chains fall, Vasudeva carries him across the flooded Yamuna to Gokul and brings back Yashoda's daughter, who escapes Kamsa and rises as the Goddess. The Harivamsha has Vishnu send the goddess Nidra to be born that night.
Brahma wakes on a lotus from Vishnu's navel, lost in dark water, and searches the stalk for a hundred years. A voice tells him to practise austerity; Vishnu appears and tells him to make the worlds. The almanacs say he began at sunrise on the first bright day of Chaitra, which is Ugadi.