History of Chapter 1: The Family Line

Chapter 1: The Family Line opens The Dark Future lore book, from Beyond Light (2020.11.10).

Summary

After the fall of the Last City, Elsie Bray is found by her estranged sister Ana Bray, whom she has not seen since the Bombardment. Ana wants to learn Stasis and shows she carries Rasputin's data core, a Warmind that did not vanish with Mars; Elsie agrees to help. Savathûn is mentioned.

Unlocking

Destinypedia says entries unlock through the Beyond Light campaign and the "Born in Darkness" questline; Ishtar Collective only says it is a Beyond Light lore entry. The triumph shows a "Progress (0/3)" objective whose meaning I could not confirm.