[s3e9] Sister Story -

The search results suggest this likely refers to (titled "A Dense and Frightful Darkness"), which heavily features the heartbreaking "Sister Story" of Ka'kwet and her separation from her family, alongside the bond between Anne and Diana.

Ka'kwet clings to the stories of her home as a lifeline. [S3E9] Sister Story

The Unbreakable Bond: Reflections on S3E9 "A Dense and Frightful Darkness" The search results suggest this likely refers to