This is a small theory I came up with a little while ago, based off of the new movie version of Les Mis. What if Javert was Gavroche’s biological father?
Think of it this way: when he lays his medal on Gavroche’s chest when he finds his body at the barricades, the tune to “he’s like the son I might have known” from Bring Him Home plays. This clearly alludes to how Javert found the boy to be incredibly brave (the medal symbolizes bravery), and possibly in another life would have considered him a son.
But remember that Gavroche IS Madame Thenardier’s son. Also recall that her relationship with her husband is NOT stable, and both could very well have had affairs prior to Gavroche’s conception. We see Javert stop by for a few minutes to inquire as to where Cosette was taken, and Madame Thenardier explains that Valjean took her. That’s all we SEE. He could have stopped by later for more information…for some reason. Ask if Cosette had any other relatives, something like that. The Thenardiers are deceitful people. Javert isn’t the type to give himself to anyone, and doesn’t indulge in “worldly pleasures”. Madame Thenardier could have drugged him at this point and taken him then. As for what Thenardier was doing…he could’ve been having an affair, too, or was on some sort of business. Maybe he was repainting that darn sign for his inn again.
This clearly would not have worked in the book, seeing as how Gavroche was a toddler around this point, and is almost thirteen at death. In the movie, however, he can’t be older than nine or ten, approximately the same gap of time between Valjean adopting Cosette and 1832’s uprising.
During the Robbery, Madame Thenardier attempts to distract Javert by showing some of her skin while her husband kisses up to him, to which he averts his gaze. In ordinary circumstances, this would be viewed as Javert showing distaste in licentiousness, or giving into any kind of sexual desire. But with the explanation above taken into account, the Thenardiers are in a much more destitute situation now, barely living off the streets. If, indeed, Javert was the father of Gavroche, chances are Madame Thenardier wouldn’t forget who he was, coupled with his notorious reputation as a cop. On her part, it could be a “take me away from this freak and his family so that I can have a better life”–after all, she did “used to dream that she would meet a prince”. Javert, meanwhile, if he remembered the event, would want nothing to do with her, seeing as how her actions would have been considered rape, ergo, a criminal offense. Why wasn’t she jailed? He couldn’t prove it, or was just ignored, the higher officials going, “Oh, a man raped by a woman? How silly! And a man of your standing? Ridiculous, Javert! >stereotypical French laugh<“
Also, up until his fatal revelation, the only time Javert shows any strong emotion not concerning Valjean is around Gavroche.
It’s not likely, but it is possible.