Sanjay appears as one of Timmy's "Back Up friends" along with Elmer (Timmy's main friends are A.J. and Chester), and is often striving to get recognition from the other three. He is a stereotypical nerdy student who likes doing homework so much that he actually reminds the teacher to give it out, much to the chagrin of his classmates. He has an obsessive relationship with Timmy as his date to the Romance Dance in "Stupid Cupid", Kimmy, looks exactly like Timmy to the point she sounds like him and has three goldfish and carries them around.
Sanjay appears to be of Indian (South Asian) descent, as "Sanjay" is a Hindi name meaning "victorious." He wears a tucked in yellow shirt with gray pants and he has round glasses with bluish green pupils. His hair sort of resembles Chester's only black. He is apparently the weakest and scrawniest of his friends.
Sanjay is considered to be Timmy's third best friend (though a back up nonetheless). In likeness to this, Sanjay had also stated that he had never been to Timmy's house (thus, showing a lack of friendship between the two). He has a little influence to Elmer because both of them sometimes get colds. He and Elmer are considered Timmy's "back up friends" and they are even more unpopular at school than Timmy and his friends.
Within the show, Sanjay is portrayed as a rather intelligent character (though not as smart as AJ). He, like most of Timmy's other friends also suffers the fate of having Vicky as his baby sitter. Sanjay also appears to have an obsession with NASA (in Dimmsdale).
He also seems to have an obsession with Timmy. In "Escape From Unwish Island", he exclaimed "At last, Timmy has come to rescue me!" Later after he was told that he was dreaming, Sanjay said "Bye Timmy, see you in my next dream!" In Merry Wishmas, he named the animal he wished for after Timmy, just like Tootie did. He even got a girlfriend that looks exactly like him in Kimmy.
He was a member of Timmy's Squirrel Scout troop but he decided to join the Cream Puffs instead because he liked their knee socks. In his first appearance in the show, Sanjay was confirmed to being the leader of the Library Club in the Dimmsdale school.
Spoilers end here.
Home and Family Life
Sanjay lives with his biological mother and his step father on a military base. His step father is a drill sergant in the military who trains Sanjay early each morning. Sanjay gets along well with his family including his older step brother who has only been seen once whom gave Sanjay a lift to school when he missed the bus. The whereabouts of his natural father are unknown at this point.