Most people are shocked when they find out a comedian is playing a vicious character in a film. I find that very surprising. Because I think nobody can deal with a tragedy as deftly as a comedian. People perceive a comedian as a cheerful person but it isn't true. It is you who is cheerful. The comedian is just throwing tragedies at you he thinks you will laugh at. One such comedian is Robin Williams. He played a killer in Insomnia, a film by Christopher Nolan. The film also stars Al Pacino as a sleepless cop visiting a small town in an attempt to solve the mystery behind a young girl's murder. But while investigating, he accidently shoots his partner and he dies. Unfortunately for him, Robin Williams's character sees him do it and uses that to blackmail him into saving him (Williams) from getting caught.
There are a plethora of films and documentaries around murderers and serial killers. None of those performances have ever seemed really truthful to me. They are made larger than life nine times out of ten. The offbeat ones concentrate on showing how serial killers come from among us and are normal everyday people. They show that evil is in all of us and there is no such thing as a beast. Insomnia largely succeeds by casting Robin Williams. Because the perception is that a comedian is harmless, it really makes you believe that he is innocent. Even after we know he has for sure committed a murder.
I think that people thinking comedians cannot do it was a blessing in disguise for this unique film. There is a scene in the film where Robin Williams starts talking to Al Pacino without any straightforward blackmailing tone, though that is the intention. He strikes a friendly tone and in the middle of the conversation confesses to the murder! And the way he talked, it felt like he was just telling his best friend that he accidentally drunk-texted something nasty last night to his ex-girlfriend and now he's regretting it. While he was describing those gory details, his tone reflected the mischievous, but not mean, tone of a child.
I also think what contributed to him being more truthful was the story as well. Even when he knows he has something on Pacino, he wants to save him rather than harming him. He isn't coming around with a knife the second he is free. There is a scene after Williams's interrogation where Pacino confronts him with the guilt he felt while saving him and thinks that he should've told the associates the truth about him. Yet, Pacino is more aggressive than Williams in the scene. Even though he is the one who will lose dearly. Williams played the role in such a way that it does not fall into the killer-being-out-and-out-evil trope or the lowlife trope. He maintains a balance between them. Another beautiful aspect is that Robin Williams does not commit any violence in the film (that we see) right till the end, when he is threatened. Which makes you really experience a jolt at the end when he does; you think, 'Oh really did it, didn't he?' That's when you realise that Williams won you over and made you believe for an hour-and-a-half that he was a good person despite all he had done.