Patrick Mercer is one of the main antagonists in Trauma Center: Under the Knife 2, alongside Reina Mayuzumi and Heinrich von Raitenau. He is the CEO of the HOA, or Hands of Asclepius, and claims to work towards changing the world of modern medicine. He is the stepfather of Heather Ross. Like Heinrich von Raitenau in X1, X2 and X3 and Reina Mayuzumi in X7, he is present to taunt the player during X4, X5 and X6.