 When Velraj showed Dhanush the script for the film, he was impressed by it and immediately offered to act in it as well as bankroll the venture. Velraj said besides acting, Dhanush suggested additional inputs to the script. Rather than demand changes, the actor collaborated with the director to develop the best script for the film. Dhanush's well-toned body was remarked upon by the media, but Dhanush clarified the workout was mostly for promoting the film rather than having done it as an integral part of his character. Velraj later commented about the requirement of a muscular appearance for a fight scene in the film's climax, resulting in Dhanush toning his body for the sequence. Amala Paul was selected to play the role of a doctor named Shalini. She described her character as "very different" from those that she had done before, and that the characters in the film were drawn from real-life archetypes.
