In those early amorphous years when memory had only just begun, when life was full of Beginnings and no Ends, and Everything was Forever, Esthappen and Rahel thought of themselves together as Me, and separately, individually, as We or Us. As though they were a rare breed of Siamese twins, physically separate, but with joint identities. (1.9)
When you think about it, Estha and Rahel actually seem to have pretty different personalities in the novel – they're definitely not the same person. And yet they balance each other out; each of them is the extension of the other.
The harbinger of harsh reality: You're both whole wogs and I'm a half one. (1.98)
"Wog" is a derogatory British slang term for a non-white person. Here Sophie Mol matter-of-factly boxes Rahel and Estha's identities into the neat category of "not white" and her own into "half-white." This is just one of the ways Sophie Mol's presence causes Rahel to feel inferior.
Two little ones, instead of one big one. Twin seals, slick with their mother's juices. Wrinkled with the effort of being born. Ammu checked them for deformities before she closed her eyes and slept. She counted four eyes, four ears, two mouths, two noses, twenty fingers and twenty perfect toe-nails.
She didn't notice the single Siamese soul. (2.27-28)
This moment contrasts the parts of the twins' identities that are visible to the eye with the parts that can't be seen. Physically, they are two completely separate human beings. Deep down, though, their inner selves are connected.
"Shakespeare's The Tempest?" Baby Kochamma persisted.
All this was of course primarily to announce her credentials to Margaret Kochamma. To set herself apart from the Sweeper Class. (6.103-104)
One of Baby Kochamma's trademark personality traits is the way she's constantly trying to control how others perceive her. She's always trying to impress people she considers to be "better" than her, like Margaret Kochamma, or to prove her superiority to those she considers inferior. Here she tries to show Margaret Kochamma that she's well-read and educated.
On the front of the book, Estha had rubbed out his surname with spit, and taken half the paper with it. Over the whole mess, he had written in pencil Un-Known. Esthappen Unknown. (His surname postponed for the Time Being, while Ammu chose between her husband's name and her father's.) (7.16)
On the surface, this moment simply tells us that Estha doesn't have a last name. (Ammu hasn't decided whether to give him her ex-husband's or her father's name.) But the significance of Estha's erasure runs a little deeper. Family names tell us who a person is in terms of who they belong to. Estha's unknown last name characterizes him as a person who doesn't seem to belong anywhere.
Rahel never wrote to him. There are things that you can't do – like writing letters to a part of yourself. To your feet or hair. Or heart. (7.62)
Rahel's inability to write to Estha shows us to what extent their identities are wrapped up in each other. Writing to him would be like writing to herself.
"Liar," Rahel said. "Liar and pretender. I did see you. You were a Communist and had a shirt and a flag. And you ignored me."
"Aiyyo kashtam," Velutha said. "Would I do that? You tell me would Velutha ever do that? It must've been my Long-lost Twin brother." (8.99-100)
Velutha's long-lost twin brother Urumban is sort of Clark Kent to Velutha's Superman. Urumban becomes Velutha's alter-ego. He can attribute actions to him that are too dangerous for Velutha to admit to having done himself.
"Where's Estha Mon?" Velutha said, with an Ambassador (disguised as a Stick Insect disguised as an Airport Fairy) hanging down his back with her legs wrapped around his waist, blindfolding him with her sticky little hands. "I haven't seen him." (9.114)
Here we see several different identities that Rahel takes on as a child. She's supposed to act as an Ambassador of India to Sophie Mol. In Estha's eyes she is a skinny Stick Insect, and she takes on the identity of Airport Fairy when the family goes to Cochin to pick up Margaret and Sophie.
Littleangels were beach-colored and wore bell-bottoms.
Littledemons were mudbrown in Airport-Fairy frocks with forehead bumps that might turn into horns. With Fountains in Love-in-Tokyos. And backwards-reading habits. (9.127-128)
Once more, we get an unflattering comparison between Sophie and Rahel here. Time and again, Rahel seems to find that Sophie Mol is everything she is not. Here we see how the family's awe over Sophie Mol diminishes Rahel's sense of self-worth.
Father Mulligan had died four years ago of viral hepatitis, in an ashram north of Rishikesh. His years of contemplation of Hindu scriptures had led initially to theological curiosity, but eventually to a change of faith. Fifteen years ago, Father Mulligan became a Vaishnavite. (17.23)
What's interesting about Father Mulligan is that up until this point, his whole identity has been wrapped up in being a priest. His vocation has been pretty much the only point of reference we have for who he is, and what his role is among the other characters of the novel. His change of faith likewise changes who he is in the book.