Anything! Debates and such, then improvised conversation. Why would RV play Stephen Fry?
I'd be Ian Hislop. Not that we want to play characters, ourselves are just fine. I do love Paul Merton though. And Hislop. And Boris Johnson. And Stephen Fry
In fact, I once had a sig with Fry, Alan Davies, Ian Hislop and Paul Merton on it.