Tainted Love.

Iru Mugan (2016) draws its inspiration from European history, particularly the Second World War, when Adolf Hitler used a drug called "Speed" to turn his troops into invincible super soldiers who rampaged across Europe, only to face defeat when said invincible super soldiers went berserk and turned on their own officers.  If you squint, you can see elements of actual history here, but it's possible that the filmmakers were not entirely rigorous in their historical research.

The Indian embassy in Malaysia is attacked by one old man who displays amazing superhuman strength and reflexes, killing several security guards before abruptly collapsing.  The old man has a heart tattoo on the back of his neck, leading RAW chief Malik (Nassar) to believe that mysterious and supposedly dead drug lord Love is responsible.  Malik calls in Akhilan (Vikram), the man who supposedly killed Love, then walked away after his former partner and new wife Meera (Nayantara) was murdered.  And because Akhilan is a disgraced former agent and loose cannon who plays by his own rules, junior agent Aayushi (Nithya Menen) is assigned as the official agent in charge of the case and Akhilan's unofficial babysitter.

The pair arrive in Malaysia and get to work.  Akhilan quickly establishes himself as the brutal and driven renegade who will let nothing stand in his way, while Aayushi provides the requisite conscience.  After a bit of investigation and violence and violent investigation they find a corrupt scientist to deliver the necessary exposition: Love is indeed back, and has recreated Speed, which works by flooding the body with adrenaline for exactly five minutes.

Despite the pulpy premise, Iru Mugan feels like a relatively grounded action movie; the action is sometimes over the top, but the story is centered on Akhilan working through his pain.  And then Love appears onscreen.  Love, also played by Vikram, is introduced wearing a gas-mask and a fabulous suit, and while the gas-mask is quickly set aside, the suits only get more fabulous.  Love is flamboyant, fey, capricious, and deadly, like the Joker if he were inspired by Bea Arthur rather than clowns.  he is, in other words, a bundle of problematic stereotypes with no apparent motivation beyond "is evil," yet still manages to be an active and interesting character with agency.  (Evil agency.)

There's no real reason for Love and Akhilan to be played by the same person.  The pair never switch places; there's no suggestion that they look at all alike, even.  Whatever the reason, Vikram turns in an impressive pair of performances, since Love and Akhilan are not just completely different people, they come from completely different genres.  Even though he's the hero, I think Akhilan is the odd man out.  Everything about him screams gritty spy drama, but he is navigating a world where Hitler's lost super soldier formula is a matter of public record.  A murderous super-chemist/fop fits right in.