Carl Bernstein

In the John Paul II days, Cardinal Joseph Ratzinger had the advantage of staying in his cupboard - the Congregation for the Doctrine of the Faith - exchanging views only with the Pope, and speaking publicly only through carefully written missives on doctrinal issues.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.