Who is the character that is torn between his/her duty and what he/she feels he/she should do?

Claude Frollo, Archdeacon of Paris, is definitely a character in the story who's torn by conflicting impulses. It is he who discovers the abandoned baby Quasimodo and raises him as his own son. One could say that he does this out of duty. But despite this sense of duty, and despite his position of authority in the church, Frollo frequently finds himself torn between what he ought to do and what he really wants to do.
As part of his duty as an Archdeacon, Frollo must remain celibate. However, the demands that this imposes on him conflict with his passionate desire for Esmeralda. Indeed, it is this desire that causes Frollo to act in ways that he knows he really shouldn't. He orders Quasimodo to abduct Esmeralda after she spurns the Archdeacon's advances; he does nothing to intercede on Esmeralda's behalf when she's tortured on a trumped-up charge of being a witch; he stabs Phoebus in a jealous rage as Phoebus is about to make love to Esmeralda.
Yet deep down, Frollo knows that he really shouldn't be acting this way; this is not how a senior member of the church hierarchy should behave. His inner conflict between his burning passions and his sense of duty drives him to madness. Even when he does the right thing, such as by rescuing Esmeralda from the cathedral, he only does so for purely selfish reasons. His final abandonment of Quasimodo, the man he brought up as if he were his own son, represents the point of no return for Frollo. The battle between duty and desire is now over, and desire has finally prevailed.