Who is Mimi?

Mimi is Ben's wife, and Sarah and Theo's mother. She is portrayed almost exclusively as kindhearted, a benevolent and caring mother. She suffers from dementia in 2010, unable even to remember Theo when he visits her. She stumbles across Waldo when she wanders out of the retirement home she lives in, and the two bond; she believes he is Theo. She dies that night by Waldo's side, happy because she believes she has been reunited with her son.