Inanna and Ereshkigal (the 'sisters' of the underworld)
Inanna (the 'light' goddess) and Ereshkigal (the 'dark' goddess of the underworld) are 'sisters' (in some accounts) or adversaries. The 'Descent' myth is the great conflict between the two: Inanna descends to the underworld and is killed by Ereshkigal [S4]S4 · Inanna's Descent to the Underworldc. 1900-1700 BCE (Sumerian)textOpen source ↗[S5]S5 · etcl.mca.edu — Electronic Text Corpus of cuneiform (transliterations + translations)corpus (Sumerian/Akkadian texts)corpusOpen source ↗. The 'sisters' relationship is a 'light/dark' duality: Inanna is the 'light' (the morning star, the life-giver), Ereshkigal is the 'dark' (the underworld, the death-bringer) [S4]S4 · Inanna's Descent to the Underworldc. 1900-1700 BCE (Sumerian)textOpen source ↗[S5]S5 · etcl.mca.edu — Electronic Text Corpus of cuneiform (transliterations + translations)corpus (Sumerian/Akkadian texts)corpusOpen source ↗.
Sumerian, Akkadian, Babylonian, and Assyrian traditions are one layered, continuous religious world. Sumerian names survive inside Akkadian texts; the succession of 'supreme' gods (An → Enlil → Marduk) is presented as political history, not mythic replacement.
The 'sisters' relationship varies by version [S4]S4 · Inanna's Descent to the Underworldc. 1900-1700 BCE (Sumerian)textOpen source ↗[S5]S5 · etcl.mca.edu — Electronic Text Corpus of cuneiform (transliterations + translations)corpus (Sumerian/Akkadian texts)corpusOpen source ↗.