His role in another film by K Balachander titled Moonru Mudichu (1976) was meatier. The film saw Kamal Haasan as the hero, a perfect foil to Rajni's villain.
Moonru Mudichu is a story of treachery, murder and vengeance of a strange kind.
Rajni plays a shady character who covets his best friend's (Kamal) girl, enacted by Sridevi. He pulls out all the stops to impress her and when that fails, he kills the unsuspecting Kamal by drowning him in the lake.
Later financial exigency forces Sridevi to marry an elderly man not knowing that he is Rajni's father. Sparks of hatred and vengeance fly when the two meet as stepmother and stepson.
Rajnikanth's villain in Moonru Mudichu is slimy and scheming, introducing a new acting style with individual mannerisms like flipping the cigarette in the air and then catching it between his lips.
He also added the trademark swagger, the rotating of his black-rimmed sunglasses, and a staccato style of dialogue delivery to his repertoire with this film.