I love the contrast between how Javert reacts to encountering Valjean before and after Valjean saves his life…
Before, when he recognizes Valjean at the barricade:
He raised his eyes, and recognized Jean Valjean. He did not even start, but dropped his lids proudly and confined himself to the remark: “It is perfectly simple.”
After, when he recognizes Valjean outside the sewers:
Javert thrust his bludgeon between his teeth, bent his knees, inclined his body, laid his two powerful hands on the shoulders of Jean Valjean, which were clamped within them as in a couple of vices, scrutinized him, and recognized him. Their faces almost touched. Javert’s look was terrible.
(…)
At length he released Jean Valjean, straightened himself stiffly up without bending, grasped his bludgeon again firmly, and, as though in a dream, he murmured rather than uttered this question:
“What are you doing here? And who is this man?”