Courfeyrac wasn't about to claim himself the best singer, but he was proud of his decent enough voice. He couldn't look at Gale and Lydia, though, without wanting to crack up at his expression... So why not use this chance to serenade Cosette?

"And it's like the fog has lifted... And at last I see the light..."

Oh, and they were still holding hands, so he just gives hers a little squeeze, smiling brighter yet.