The older sister of Deanna Troi, who drowned as a child and whose memory Lwaxana Troi kept hidden for decades.
Kestra Troi was the first daughter of Lwaxana and Ian Andrew Troi. She died in a drowning accident as a young child, when Deanna was still an infant, and Lwaxana was so overcome with guilt that she suppressed the memory and erased all trace of Kestra from her life.
In Dark Page, Lwaxana's buried grief surfaces and leaves her in a coma. Deanna enters her mother's mind and discovers Kestra's existence for the first time, helping Lwaxana face the painful memory and heal.