I always found the extraordinary loss of life in the First World War very moving. I remember learning about it as a very young child, as an eight- or nine-year-old, asking my teachers what poppies were for. Every year the teachers would suddenly wear these red paper flowers in their lapels, and I would say 'What does that mean?'

I've done my share of period stuff. I'm not sure why, but people say I have a period face. The bread and butter of British TV is Jane Austen adaptations and bridges and bonnets and boats and horses.

The character, as written on the page, is just a blueprint for a human being.

In 'Thor,' that was my own hair. I grew it out. But I have naturally curly, blonde hair, so I'll never look like that. By the time I got to 'The Avengers,' I had come off two other films, which required me to have it very short. So I dyed it again and it was long enough to use a part of my hairline.

I am so profoundly aware of my lack of skill to make any material difference. I am not a doctor. I can't influence foreign policy. I can't build schools. I can't chemically engineer the protein paste that helps people with acute malnutrition. But I can talk about it, and so can you.

I wish we could be decent to each other.

I gave myself permission to care, because there are a lot of people in this world who are afraid of caring, or afraid of showing that they care because it's uncool. It's uncool to have passion. It's so much easier to lose when you've shown everyone how much you don't care if you win or lose. It's much harder to lose when you show that you care, but, you'll never win, unless you also stand to lose. Don't be afraid of your passion.