In my opinion, Jeyaraj is an incredibly minor character in The Painter of Signs. I believe this is why your question hasn't been answered for a month or so. What Jeyaraj is like and his relationship with Raman is so insignificant, that it is more important to discuss the other characters of the piece. Therefore, let's look at the plot so you can determine exactly how Jeyaraj fits in
Raman, of course, is a painter of signs and takes pride in his work as a professional and a college graduate. Living with his elderly aunt, Raman tends to the house and his aunt and his nephew. Raman is always avoiding the mysteries of life and focuses, instead, on rationality. Raman eventually writes his aunt's biography through dictation. She is very religious, and causes Raman to ask this question:
How could the Age of Reason be established if people were like this? ... Ultimately I can evolve a scheme for doing without money [and] get away from sex thoughts [that are] too much everywhere.
It is Raman's meeting of Daisy, not Jeyaraj, that changes everything. Daisy wants to improve women's lives. Through the signs she orders, Raman learns lots about family planning and relationships and love. Even though Raman never wanted to get married, Daisy makes him question his own rationalism.
In conclusion, the New India and the Old India are nicely portrayed in the characters of Raman and his aunt, and have little to do with Jeyaraj. Daisy represents the liberation of women in that New India. The end is interesting for Raman (and a bit depressing). His aunt leaves on pilgrimage. Daisy leaves for her career. Regardless, Raman is left alone with his rational thoughts.