For the next hour, they sat together, the conversation flowing naturally. Grace asked questions about her early childhood—what games she'd liked, what songs Elise used to sing to her, what her first words had been. Elise answered everything with joy, clearly treasuring the chance to share these memories.

Helena told funny stories about David, painting a picture of a brilliant but sometimes scattered man who would get so absorbed in his work that he'd forget to eat. Luna described the ...