A cumulative trophy that makes the entire game much harder. You will either need to play the game twice or more depending on the amount of time you spend within the districts and the choices you make. To fulfill the requirements, you must NEVER KILL, by your hand, a citizen of London. This means, for the story choices:
Clay must live (spare)
Dorothy must live (either spared or charmed)
Hampton must live (either spared or charmed)
Take Aloysius as your Progeny (don't charm or Embrace)
McCullum must live (spare)
Take Edgar as your Progeny
Along with these choices, you must not kill any of the turned citizens or Embrace any of the living. You may hear some lines from bosses or characters that remark on what you have done (such as if you charmed Dorothy, Mary will comment on how you twisted her mind), but as long as you have not fed or slain any of them, you should get this trophy at the very end. Reid will comment on how, after his sister's death, he has not fed on anyone in the final scene and once the stills start to play, this will unlock with the one stating that you completed the game.
For some reason, it does not seem to count the Vicar involved in the Mary fight. Therefore, do with him what you must, for if you leave him alive, she'll certainly finish the job.