Morris Sullivan was born to a wealthy family that, in fear of diluting their blood with that of outsiders, married cousins for generations. Growing up on Endoria Street, he grew to be large and strong, developing a temper and a cruel streak toward animals, but his brain remained underdeveloped. He was once painted by Anton Sokolov.
In 1811, he met Vera Moray, becoming her apprentice even before her transition into Granny Rags, ]and - staying true to his cruel nature - Sullivan became the Royal Interrogator at Dunwall Tower, serving as both a torturer and an executioner.
In his duty as Royal Interrogator, Sullivan tortured former Lord Protector Corvo Attano with a hot iron. Corvo is tortured for six months as the Lord Regent wants him to sign a confession for the Empress' murder. However, Corvo remains standfast and Burrows eventually gives up, ordering Corvo's execution. After sending Sullivan out of the room, Burrows confesses to Corvo that he and his associate Campbell are behind the death of the empress.
While infiltrating Dunwall Tower to assassinate the Lord Regent, Corvo can find a letter to General Tobias, which states that the torturer has been coming into the guard barracks at night. One guard woke up to see Sullivan leering at him in the dark. Other guards have reported that personal items have gone missing, with odd things like a bunch of teeth or three painted rat-heads left in their place. Reading this letter adds the optional mission to kill the Royal Interrogator.
If Corvo choses to kill Sullivan, he must sneak into the basement of Dunwall Tower where Sullivan lives with his pet wolfhound. Corvo can sneak up onto Sullivan and silently kill him or engage into a fight with Sullivan. The fight against Sullivan is easily one of the hardest fights in the game. He is immune to most of Corvo's supernatural abilities, for example Bend Time, and is able to use magic on his own, possessing the ability to pull Corvo towards him. Sword, crossbow and spring razor deal less damage to Sullivan and he is completely immune against sleeping darts as well as against frontal fatal attacks. Opposed to his defense, his attacks are somewhat simple; he swings a heated metal bar like a sword, and while he can block, dodge, and kick, his skill at doing so is noticeably poor compared to other enemies.
After Sullivan's death, Corvo can take a rune from the torturer's Outsider shrine.