It takes him a moment to pull together the various threads: right, Fauchelevent, who was at the barricade for Marius, knows Javert because he one was mayor of a town where Javert worked for the police. And they argued over the treatment of a poor woman, mother of Marius Pontmercy's wife.

"It was Fauchelevent," he says slowly, "who asked for the spy at the barricade. And--let him go? Well. --As for the church, I can think of--oh--many reasons. But I don't know the man at all."

Except that he's a good man. A good man on the individual level: a man to take in an orphan, release an enemy. A man saving lives that were in his hands to save.