Pastor Nick claims that he lost his family as a result of addiction to Vine.
As a religious leader, Pastor Nick used his influence to oppose any modification of the walls, be it permanently sealing the gates or even mounting cannons on the top. Though he claimed it was blasphemy for humans to "maim" the wall, the real reason was to reduce the risk of workers discovering the Titans within during renovations.
He also touches children in his spare time (may not be true).
After Annie Leonhardt breaks a portion of Wall Sina and exposes a Titan within, Pastor Nick orders that it be covered up immediately to prevent the sunlight from awakening it. Realizing that Pastor Nick knew the truth about the Titans within the Walls the entire time, Hanji Zoe threatens him in an attempt to get him to reveal more, but he refuses. 
When Hanji brings Pastor Nick with her through the Hermiha District so he can see the suffering of the families forced to evacuate because of the suspected breach of Wall Rose. While he will not betray the secrets of his organization, he tells the group about a girl, hiding under an assumed name, who would be able to speak about the secrets. Eren and the others realize Pastor Nick is speaking about Historia Reiss.
Pastor Nick is later seen with Rivaille and a few Military Policemen 
Pastor Nick was part of an religion called "Aberot Sina Paladin" that believed
God brought humanity the walls and punished humanity with the titans.They
Also believe that the collosal titan was Satan,and are subtquals of miasmic milleniasm.