I will start off first. People state that rajini and prabhu have a very good chemistry but i feel the rajini and kamal chemistry in their earlier movies especially balachander movies was a large reason for the movie's success. Rajini's realistic protrayal of negativity,sarcasm contrasted by kamal's affectionate and compassionate performances was a joy to watch. Both actors had good timing and knew how to end each others expressions/dialogues off. A good example would be avargal and aval oru thodarkathai.