Who is Dr. Lauchlin Grant from Ship Fever and what is their importance?

Dr. Lauchlin Grant was a youngish, wealthy, well educated man, who studied medicine in Paris. He was born in 1820 and raised in Quebec. Lauchlin is romantically interested in Susannah Rowley, his childhood friend. He is described as pale-skinned, red-headed, and of normal height, weight, and build. Women do not find him especially attractive. Grant does, however, possess a keen intellect and has been provided with excellent medical training. In the end, Grant dies of typhus.