When I first saw him, I thought: "Is that her doctor? He's not in this act!" But when Violetta first approached him, stage left, he was so indifferent to her suffering that I started thinking he was the figure of Death instead. Then he turned out to be the doctor after all. Hmmph.
But what he really was, was the opera's florist. When Alfredo makes his declaration of love to Violetta, she hands him a flower and tells him to return when the flower has withered. (O ciel! Domani!) So where did that flower come from? There were no flowers on that stark set, no vase to hold them if there were, no table to hold the vase. That's why the doctor was onstage; someone had to give Violetta that flower. And it wouldn't do to have him lurking around in the first act and then just disappear, so he continued his lurking ways right to the end and even gave Violetta another flower somewhere along the way. But in the time the two lovers had together in the country, what was the pattern of their sofa throws and robes? Flowers!
I've never seen a performance of Traviata that included "O mio rimorso", and that's a shame; it's not long and wouldn't add much to performance time. It seemed to me part of the gambling scene was cut in Saturday's performance.
Wouldn't you think that Violetta would have more than one party dress? But we now know Alfredo wears boxers and not briefs.