Who is Walter Emerson from Crocodile on the Sandbank and what is their importance?

Walter Emerson is Radcliffe's younger brother. He is an expert at hieroglyphs and philology, and in order to understand the origins of the ancient Egyptian language, Walter joins Radcliffe for the Egyptian excavation, where they meet Amelia and Evelyn. Walter immediately falls in love with Evelyn and knows nothing outside of the fact that he loves her more than anything on earth. As he pursues Evelyn, he is made aware of Evelyn's shame...... and his only response is to ask Evelyn why she could not have trusted him with the secret. The couple eventually marries and has a family.