Āruṇi (Aruni) was one of the sons of Vinatā (Vinata), sired by Prajāpati (Prajapati; Ruler of the People) Kaśyapa (Kasyapa).

Mahābhārata (Kinjawadekar)(1.65.40)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(1.60.40)

Āruṅi was also among those who were present during the celebration of the birth of Arjuna, the third Pāṇḍava (Pandava).

Mahābhārata (Kinjawadekar)(1.123.73)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(1.117.77)