In book 8, chapter 6, of The Hunchback of Notre Dame, the Gypsy girl, Esmeralda, is saved from hanging by Quasimodo, the hunchbacked bellringer of the Cathedral of Notre Dame in Paris.

In book 9, chapter 2, Esmeralda has recovered her senses after being carried away by Quasimodo to sanctuary in the Cathedral.

[S]he turned to Quasimodo, who was standing in front of her, and who terrified her; she said to him,—

“Why have you saved me?”

He gazed at her with anxiety, as though seeking to divine what she was saying to him. She repeated her question. Then he gave her a profoundly sorrowful glance and fled.

Quasimodo doesn't answer her because he doesn't know what Esmeralda is saying. Quasimodo is deaf.

In chapter 3, after an unaccustomed good night's sleep, Esmeralda wakes up in a tiny room near the roof of the Cathedral, where Quasimodo has taken her. Quasimodo tells her that he's deaf but that he can understand what she's saying if she uses gestures in addition to talking to him.

"And then, I shall very soon know your wish from the movement of your lips, from your look.”

Then Esmeralda asks Quasimodo the same question.

“Well!” she interposed with a smile, “tell me why you saved me.”

This time, Quasimodo answers her.

“I understand,” he replied. “You ask me why I saved you. You have forgotten a wretch who tried to abduct you one night, a wretch to whom you rendered succor on the following day on their infamous pillory. A drop of water and a little pity,—that is more than I can repay with my life. You have forgotten that wretch; but he remembers it.”

Quasimodo saved Esmeralda from execution because she once pitied him, gave him water to drink, and gave him a sense of dignity in his suffering.

Quasimodo also loves her, of course, but he can't bring himself to say this.