As Sigmund Freud developed his theories in Austria he gathered a set of followers who studied and debated his theories. Among them was Charles Braun. He was fascinated by the concept of transference, in particular countertransference. Whether it was his research or the manifestation of a power, but Charles eventually found he could literally enter the mind of another person and control their actions. At first he did it as research but eventually his own sense of reality became twisted. Taking over other people’s minds and bodies became exciting and exhilarating. Then came the day he realized he was getting older and that he could extend his life by permanently taking over a person’s body. Since then taking over other people’s bodies has become a way of life for him.
Alienist does not have stats as per a normal NPC. He has the stats and abilities of whatever body he has taken over. Each turn he can dominate a person as a Standard, At-Will power. If the target has powers then (save ends). If the target does not have powers, then they get no saving throw.