It's really good to talk about it [ hydraulic penises and prosthetic butts], and it's very gratifying when people ask us about the other aspects of the film [Swiss Army Man], but [those things] are part of the movie and they're important and hilarious, a very fun part of the movie, so there's no sense from us of not wanting to talk about that. I think it's exciting that those things exist in a film that is also very heartfelt and emotional and profound.

Being in Harry Potter is like being in the Mafia. Once you are in, you are never really out.

The most wonderful thing I hear is people coming up and saying 'Thank you for my childhood', which still blows my mind but is very sweet.

For me, you go to university to meet lots of different people from different backgrounds. I think that's one of the most important things you get there. And you also get some sense of direction regarding what you want to do when you leave. I sort of know what I want to do in my life - I want to act and ultimately I'd like to write. And in terms of meeting people from different backgrounds, that's what you get on a film set. So the two most valuable things that university would have given me I've sort of achieved by being on a film set.

Because of the life I've had, I'd grown up quicker than most people.

Mostly, I'm drawn to great characters and great worlds that use weird things for their language - whether it's dance, whether it's pop music with Justin Bieber, or whether it's magic.

In some ways, you get to find your voice better in [a sequel] because you have to define how you're doing it differently.