One cannot predict on how and why predict become friends. But to become friends, either they should have similar traits or choices.
Here's one friendship that has blossomed and bloomed! Actresses Reema Sen and Sonia Aggarwal are well-known in the Kollywood circuit for being great friends. Interestingly, Reema Sen was acting in Selvaraghavan's Aayirathil Oruvan when he was fighting for a divorce with Sonia.
They became close during the making of the film. Sonia found solace in Reema's company during the most difficult phase in her life. They are still very close and meet up often in Mumbai.