 When allowed to remember being kept by Kemmler, he became out-right murderous and spiteful, nearly killing Harry but for limitations Bob begged Harry to make before ordering him to remember.When stolen by a necromancer, Bob became largely cold and business-like, simply giving information as needed, but returning to his personality under Dresden upon being dropped.Changes in his personality are accompanied by a change in his eye color, such as being orange when owned by Dresden but red when remembering Kemmler, or blue when he was in the hands of a necromancer.