What is the most famous theme in Henry James’s fiction? And what is his favourite approach in characterization, which makes him different from Mark Twain and W.D. Howells as realists? Give two titles of his works in which this theme and this approach

What is the most famous theme in Henry James’s fiction? And what is his favourite approach in characterization, which makes him different from Mark Twain and W.D. Howells as realists? Give two titles of his works in which this theme and this approach are employed.

A.His most fanous theme is international theme.
B.Psychological approach.
C.The Portrait of A Lady: Daisy Miller.