Dr. David Rubin is a old friend of Jamie Hamilton's from school.
Rubin is described as having a crush on Hamilton, coincidentally, he claims that his mother also asks about Hamilton as well. Since their school days, he has built up "quite a big practice" for himself.
Rubin is surprised when Hamilton calls him and immediately asks her to dinner. However, the phone call concerns getting medical attention for a poisoned Xaviar. He offers to help and, with the help of a fellow doctor and Troy, they manage to save Xaviar's life (The Day They Kidnapped Cleopatra, unproduced script).