Rahul Gandhi recently spoke of putting away his anger at his grandmother's assassination. What do you say to this "forget and move on" approach for those who survive genocides and mass-murders?

Raj, the narrator of Helium, faces a huge predicament. His own father, a senior IPS officer, facilitated the violence in November 1984. In the story, under the watchful eyes of the cops a mob directed by senior Congress party leaders had burned to death Raj's beloved IIT professor . Later a traumatized Raj asks a question which might be of some significance to the younger generations in India: how do sons and daughters deal with the crimes of their fathers? Raj is unable to move forward until he has processed this question. Ultimately, he decides to acknowledge the crime of his father. He no longer hides it, or distorts it, and he is no longer silent about it.

Are there any autobiographical strains in your book?

I was a teenager in Delhi in 1984. I saw ash particles floating in air. Like Raj, the central character of my book, I too studied science and engineering. At the same time, Helium involved a lot of research and relied on survivor and relief worker testimonials . It is based on oral histories and private archives. The hybrid form allowed me to pose questions like: 'What happened?' and 'What could have happened?' It also allowed me to create distance.

You talk of nearly abandoning the project. Was it difficult extracting these memories?

What we are really talking about here is complicated grief and collective trauma. Unfinished mourning. Not just memory, but also postmemory and transmission of trauma. It is never easy.

Why did you choose to weave the facts you collected into fiction?

For me, Helium is really rough-and-ready notes for a book that belongs to the ambiguous, interstitial zone between history and traumatic memory — between the 'objective' and the 'intimate' . This form allowed me better access to the pogroms of November 1984 and the years that have followed. To try to do it otherwise, as in say a human rights report, is a paralysing affair, and affects our capacity as human beings to engage fully with the crime of crimes.

Why did you bring in the work of Italian scientist and holocaust survivor Primo Levi into the book?

Primo Levi's The Periodic Table is a fine way for a chemist to organize memories. The book has 21 chapters, each titled after a chemical element. Argon, Hydrogen, Potassium, Sulphur, Tin, Nitrogen, Nickel, Mercury, Gold...He sees strange parallels between humans and the properties of these atoms. Helium is also a homage to another favourite writer of mine: WG Sebald. Both were engaged with the subject of genocidal violence and other calamities.

There is a strong indictment of the Congress establishment in the book. Do you believe that the apology hasn't worked as a salve?

To this day, senior Congress leaders involved in the pogrom and their loyal protectors enjoy infinite immunity. Non-deliverance of justice often creates uncomfortable situations like this one in the book: the Sikh victim's wife Nelly is retiring as a chief librarian and the chief guest for the occasion is a cabinet minister who had incited the mobs. November 1984 requires an enormous 'work of mourning', not just by the survivors and the targeted collective, but by the entire Indian nation.

You refer to the emerging saffron brigade in the book. Do you feel a sense of unease at this?