"There's years - over 50 years - of backstory on him all there to use, and I like doing that. Him and his sister [Scarlet Witch] have been abandoned by their parents and their father, and they grew up in Eastern Europe defending and looking out for themselves and each other. His sister really is his guidance - emotionally she's the one who looks after him, and vice versa. He's very overprotective physically - he doesn't want anyone touching her. He has real anger frustration - I like that. I always thought it'd be quite funny if you saw him eating loads and people asked him why and he'd explain it's because he's burning so much energy all the time. Or ideas that you'd see him come back round - but he's already nipped out and got his lunch somewhere else. He just got bored - his attention span is so f---ing quick."
He also spoke about the physical transformation required, and how to not make his appearance seem forced.
"That's what we're in talks about really, right now - how I could become that character and not feel forced. I might not look right with white hair, and the accent may be wrong... it just doesn't work like that. Unless you're Jim Carrey or Nicolas Cage and go 'This is the character', people go 'OK, OK...' When people haven't been shown your range like that, then they're a bit more skeptical - they may not want you to push the boundaries in that way. But that's what I'm interested in as an actor."