Yes... [Sara's expression is unreadable. it's up to Fuu to decide whether she believes the motives Sara is about to claim are true]

Robert had been curious about the house for a long time. He wanted to stay there, to find out more about what it--what I--could do. He hoped that I could save his world. But he wouldn't have stayed on his own. So, I told him that I would heal his daughter--if, in exchange, he stayed in the house for the rest of his life.