Both the Aoi parents have brown hair. Only the father have lighter brown hair and the mother have darker shades of brown hair. They were both soft-spoken as seen when they talked with both Natsume and Miyoko.
When Natsume came to visit them and get his key for his house, father Aoi mentioned about how thin Natsume looked like. He showed his concerned whether Natsume was eating enough at the Fujiwaras.
Also when Natsume seemingly stunned from something, father Aoi was concerned and panicked for Natsume. Mother Aoi also rushed to get the first aid kit when noticed Natsume got scratched by the big-fat cat that tress passed in.