Deronda was wondering what he should have thought of her if he had never heard of her before: probably that she put on a little hardness and defiance by way of concealing some painful consciousness--if, indeed, he could imagine her manners otherwise than in the light of his suspicion. 
Deronda wondered what he would have thought of her if he had never met her before: probably that she put on a little hard defiance to conceal some painful knowledge. 