In Hindu mythology, Sati was a goddess born as a human at Brahma's behest. Sati grew up devoted in worship to Shiva and spurned the advances of rich kings to the point where she left for a forest to escape the constant proposals. Eventually, Shiva consented to make her his bride, and, elated, Sati went to share the news with her father. However, upon her father's expression of his disapproval of her marriage, she immolated herself, praying to one day be reborn as a daughter to a father she could respect. Sati would eventually be reborn as Parvati.
Sati was also an Indian practice, literally meaning "virtuous woman," in which a recently widowed woman would throw herself onto her husband's funeral pyre to keep from being a burden to her family. The death of her husband would explain her black clothing and the flames.
"A goddess in Indian mythology, the first consort of the god Shiva. She is a grandchild of Brahma, one of the supreme Indian deities. Sati's father Daksha, a son of Brahma, worshiped the supreme deity Vishnu and despised Shiva, who was a supreme god in his own right. When Shiva was not invited to Sati's betrothal, he suddenly appeared and caught the garland she threw, thus sealing their union. Later, when Daksha held a sacrifice and invited the gods, Shiva was again the only one not invited. Outraged, Sati protested to defend her husband's honor, but was ridiculed by the gods. She then committed suicide by self-immolation. Upon hearing of this, Shiva become enraged and wailed in grief. Sati was later reincarnated as Parvati and once again became Shiva's consort."
"In Hindu mythology, she was Shiva's first wife. She threw herself into the fire during a feud between Daksha and Shiva, but was reborn as Parvati."
—Devil Summoner: Raidou Kuzunoha vs. The Soulless Army devil chart
Sati begins appearing in random encounters in Harumi-Cho. Due to her ability to drain Gun attacks, Raidou will not be able to capture her through use of Ice Bullets and will need a demon of the Frost Order to stun her before Confinement. She will later appear in Kasumidai and Dark Kasumidai.
Sati is the third Persona of the Priestess Arcana. As Sati gains ranks, all of her stat increases go to Vitality and Luck. Upon being returned to the Velvet Room at MAX Rank, she will yield a Full Moon Tablet.
"Shiva's first consort in Hindu myth, she threw herself into a sacrifical fire in protest of her father's treatment of Shiva. Reborn as Parvati, she was reunited with Shiva."
—Persona 4 Golden Compendium
The third Persona associated with the Aeon Arcana, Sati can only be created once the protagonist has reached level 31 and achieved the appropriate level of the Social Link with Marie. As with all other Aeon Personas, she can only be obtained through fusion.