Who is Tapan Chatterji from A Suitable Boy: A Novel and what is their importance?

The youngest child of the Chatterjis, Tapan is a student in boarding school when he become the object of one of the senior boy's lust. A normally good student who enjoys school, Tapan becomes reclusive and sad. Amit and Dipankar, his older brothers, get Tapan to admit what has been bothering him, and they are able to persuade their parents to allow Tapan to change schools.