This is a mix of Sweeney Todd and the Hunchback of Notre Dame AU but this one is based more off the original novel by Victor Hugo and the musical adaption.
In Paris France Andre Bourgeois is the head of the church who is married and has a new daughter. Gabriel Agreste is happily married to a beautiful gypsy woman and newborn son. Andre unsatisfied with his marriage begins to lust after Gabriel's wife which he thinks is the work of evil. He attempts to seduce her but she rejects him, his wife finds out and angrily abandons her husband and daughter. Andre blames Gabriel's wife for this convincing himself that she's a witch who cursed him. Andre kills her which is witnessed by Gabriel who in turn tries to kill Andre but he is arrested and framed for the murder. Gabriel is banished from Paris while his newborn son becomes Andre's ward but because the child reminds him so much of the evil deed he committed and to avoid anyone finding out the truth, he isolates him away in the church.
Years later the boy named Adrien grows up kept in the dark with no one aware of his existence except Andre and his cat Plagg. He longs for freedom but is denied it by his foster father. During a festival Adrien sneaks out of the church to have some fun where he meets Marinette a beautiful young gypsy girl who unintentionally captures the hearts of several men: Nino a poet, Kim Captain of the guards who is engaged to Andre's daughter Chloe, and Adrien. While Nino and Adrien truly care for Marinette Kim and Andre just want her out of lust. During the feastival Adrien is accused of a false crime and as punishment he is tormented but Marinette saves him. Later Paris begins to go into a panic when a mysterious man going by the name of Hawkmoth who has been killing people he deems sinners. After watching Marinette outfit Andre's men and Adrien cleverly sneak out of the church, a kind priest named Fu entrusts them with weapons and disguises so that they may masquerade as heroes and stop Hawkmoth. In this Adrien and Marinette know each other's identities because secret love is annoying.