Fauchlevent

Fauchlevent is one of those minor characters that is so important he's even in the musical :). He is the man who talked meanly and disrespectfully about Jean Valjean when he was the mayor, but when he was trapped under a cart Jean Valjean risked his life and discovery to save him.
After Fauchlevent recovers he is lame (you know what I mean, he foot doesn't work very well). Jean Valjean helps him to find work in a convent.

Jean Valjean is ultimately rewarded for this service. When he is running from Javert with Cosette, he ends up in that same convent. Fauchlevent repays his service by ensuring that he can stay at the convent-- one of the safest places he could hide from Javert.

So Jean Valjean assumes the role of Fauchlevent's brother and stays at the convent, which is where Cosette grows up. The nuns nicknamed Fauchlevent "Fauvent" which is a name Jean Valjean uses when he leaves the convent.

"...Father Fauchelevent was an old man who had been an egoist all his life, and who, towards the end of his days, halt, infirm, with no interest left to him in the world, found it sweet to be grateful, and perceiving a generous action to be performed, flung himself upon it like a man, who at the moment when he is dying, should find close to his hand a glass of good wine which he had never tasted, and should swallow it with avidity. ...We have just called him a poor peasant of Picardy. That description is just, but incomplete. ... He was a peasant, but he had been a notary, which added trickery to his cunning, and penetration to his ingenuousness. Having, through various causes, failed in his business, he had descended to the calling of a carter and a laborer. But, in spite of oaths and lashings, which horses seem to require, something of the notary had lingered in him. He had some natural wit; he talked good grammar; he conversed, which is a rare thing in a village; and the other peasants said of him: "He talks almost like a gentleman with a hat." Fauchelevent belonged, in fact, to that species, which the impertinent and flippant vocabulary of the last century qualified as demi-bourgeois, demi-lout, and which the metaphors showered by the chateau upon the thatched cottage ticketed in the pigeon-hole of the plebeian: rather rustic, rather citified; pepper and salt. Fauchelevent, though sorely tried and harshly used by fate, worn out, a sort of poor, threadbare old soul, was, nevertheless, an impulsive man, and extremely spontaneous in his actions; a precious quality which prevents one from ever being wicked. His defects and his vices, for he had some, were all superficial; in short, his physiognomy was of the kind which succeeds with an observer. His aged face had none of those disagreeable wrinkles at the top of the forehead, which signify malice or stupidity."