He presses her hand back for a moment; deal, then! "She's a sensible girl. It's nothing against her if the men of her family don't know enough to rely on that yet; we'll all have to hold them to it, that's all." He's smiling as he says it, but: seriously, Marius and Valjean both need to be spoken to.

"One thing you should know-- and this isn't some rumor, this isn't from the book, it's the truth from my own friends, who were there, and saw it-- your Cosette's father acted so at the barricade that even Javert couldn't accuse him of much. He spared the spy's life; why, I don't know; but he saved many men before then, and harmed none; so that all that could be easily leveled against him would be a charge of aiding the wounded on the wrong side of the barricade, if the law wanted to be honest-- though when has it ever chosen that? But you should know, at least, in case he tries to turn his work there into one of the great crimes he seems to think he's committed. You're not one to be taken in by that line, but now you have the truth of it, to counter him, if you must."

That's an easy thing to share, the good deeds of a kind, if rather foolish and confused, man. There's other things that will be harder for her to consider, but this at least can't even be much of a surprise.