Mammachi and Pappachi are the grandparents. Mammachi is blind, makes pickles for the Paradise Pickles factory, and plays the violin. Pappachi is dead but while he was alive he was an entomologist, beat his wife, and discovered a moth that is oft-mentioned in the book.
Chacko and Ammu are their children, brother and sister. Chacko studied at Oxford and now runs the pickle factory, though it's still Mammachi's factory. Ammu moved to Calcutta, married an alcoholic, had twins, got divorced, and moved back (sort of in disgrace) to Ayemenem to her parents house.
Estha (the boy) and Rahel (the girl) are Ammu's twin children. The book flashes back between their childhood (when they were seven) and many years later, when they're adults, seeing each other for the first time after being separated 23 years.
Baby Kochamma is Ammu and Chacko's aunt, Estha and Rahel's great aunt. She lives in the house, and in the later years she watches a lot of TV with the family cook, Kochu Maria.
Sophie Mol is the daughter of Chacko and his English ex-wife, Margaret Kochamma. They live in England. Margaret remarried a guy named Joe who died recently in a car accident, so she and Sophie are heading to Ayemenem to visit Chacko (who hasn't seen either of them since Sophie was a baby). Much of the book takes place while Estha, Rahel, Chacko, Ammu and Baby Kochamma are in the car on the way to the airport to pick up Sophie Mol and Margaret. On the way to the airport is when they stop to see the Sound of Music and see the Communist demonstration.
Velutha is the son of Vellya Paapen, and he's part of the Paravan (Untouchable) caste. He does carpentry and other odd jobs for the family and lives across the river. He's a pal of Estha and Rahel, and he's the one Rahel thinks she spots at the Communist demonstration.
Comrade K.N.M. Pillai is a local printer and head of the district Communist Party. His son is named Lenin.
