Diana Lindsay is a romantic interest from Bull's past and is the person solely responsible for the one and only trial loss that he has suffered in his career. Diana is a senior partner in a law firm located in Callisto, Texas which is notorious for the number of patent infringement lawsuits it files, as well as the number of of those suits it wins. Bull knows that Diana will stoop to any means necessary to win and in #104 he uses that against her.Diana reappears in #115 when a sociopath billionaire who is trying to outsmart Bull discovers their history and brings her to New York during an escalating battle of wits with Bull. Sparks fly once again, however Bull soon becomes concerned that Diana may be in danger when her wealthy client proves that he is willing to stoop to any level to win including murder.