Book IV Summary

Chapter 1: Good Souls

Backstory time.
Sixteen years before this story takes place, a group of old women are gawking at an abandoned child who is severely deformed. Oh, and it just so happens that it's Quasimodo.
Everyone who passes says some pretty insensitive things, and there is talk of simply throwing the child onto a fire.
Then a young priest walks through the crowd and announces that he has adopted the child like it's no big deal. That priest is Claude Frollo.

More backstory.
Claude Frollo came from a well-off family and was destined for the priesthood from an early age. He was super serious about studying and rose through the ranks like it was nobody's business.
When Frollo was nineteen, his parents both died from a plague that was going around, and he was left with an infant brother. This changed Frollo's life. He decided to devote his love to his younger brother (who is, in fact, Jehan, that rowdy student from earlier).
When Claude sees the abandoned child, he imagines what would happen to Jehan if he (Frollo) were to die, and he adopts the child out of compassion. He names the child Quasimodo.

Fast-forward to the present (the present being 1482), and Quasimodo has spent so long cooped up in Notre-Dame that he has come to resemble it.
When Quasimodo became the bell-ringer at age fourteen, the bells made him deaf. Because he's deaf, he can't really talk, either. So much for Frollo teaching him how to speak, we guess.
Quasimodo has a skewed view of the world, and because people have always been cruel to him, he hasn't exactly turned out to be the nicest person himself.
Notre-Dame is Quasimodo's entire universe. But his favorite part of the cathedral, by far, is the bells. He even gives them names.
Quasimodo can be seen all over Notre-Dame, and his presence gives it a soul—even if it's a sinister soul.

Even though Quasimodo hates all of mankind, the one exception to his rule is Claude Frollo.
Quasimodo is so grateful to Frollo that he's more obedient to him than an animal to its master.

Come 1482, and Quasimodo is about twenty. Claude Frollo is about thirty-six.
When Frollo had adopted his younger brother Jehan, he thought that Jehan would turn out to be pious and docile. As it turns out, Jehan is wild, debauched, and rowdy.
In light of this disappointment, Frollo becomes even more invested in his studies, and he eventually turns to the dark art of alchemy. Basically, he becomes obsessed with Nicholas Flamel, who was a real alchemist and not just a character in the first Harry Potter book.
Frollo has been known to frequent Nicholas Flamel's old house and to stare at the entrance of Notre-Dame looking for symbols. He even has a secret room where a red blinking light has been seen at night. Something is up…
Despite the fact that he seems to be more than a little obsessed with the dark arts, this doesn't stop Frollo from hating on gypsies.
The truth of it all is pretty much that Frollo's gotten meaner as he's gotten older. He hates women, and he especially hates women who might use goats for witchcraft.
Yes, it's oddly specific.

Needless to say, when Quasimodo and Frollo walk down the street, they don't garner a positive response from the good people of Paris. Fortunately, one is deaf, and the other is too lost in thought to notice.