On the surface, Kieran has a charming, flirtatious, and playful personality. He always calls people "darling" or "my love". However, these personality traits hide a much deeper and more serious character - he drops all pretenses and is much more serious, somber, and straightforward. This is not to say his former behavior was false, rather he emphasized his surface-level traits in order to hide his deeper self. He sees himself as a monster. He never wanted to be an assassin.