When it comes to acting, people talk about the suspension of disbelief that you ask of the audience. Before that starts, you have to, as an actor, suspend your own disbelief.
Helena Bonham CarterJ.K. Rowling said Bellatrix's role was going to be significant in the last one, when I showed some reluctance in playing a tiny bit part. Up front, they said, 'You're very significant in the last one.' But significant could mean a lot of things. That could just mean a significant plot point. Doesn't necessarily equal big part.
Helena Bonham Carter