At the end of chapter 20, the last thing that Estha yells at his mother and sister before the train pulls away is "Feeling vomity!" Recall that this is the same claim he made when he was abused by the Orangedrinklemondrink Man. After the train pulled out, Rahel doubled over in emotional pain, so I would assume that Estha did the exact same thing at the exact same time. The same thing happened when Ammu died, and they both felt a mutual compulsion to see each other in the hotel after the events at the movie theater. I bet they had some serious demons in the twenty or so years between the departure and the reuniting after Ammu's death that Roy didn't tell us about. The departure was one of the most deeply impacting events in the book, even though it was so short.

Baby Kochamma's inexcusable behavior completely desecrated this family and the deep and abiding bonds that it shared. It's mostly her fault that Estha became a mute, and it's her fault Estha and Rahel were separated for the majority of their lives. I don't get it either. Why did Baby Kochamma care so much about the extra-caste bond between Ammu and Velutha? Was it because it wasn't traditional? Then why BK care about Father Mulligan so much? Does the whole affair have anything to do with the fact that Velutha is not your average Paravan? It just doesn't make any sense.