Daniel and Marie are Alain’s younger siblings.
When first introduced, they were mere babies, most likely two to five years old. They were ragged due to poverty, but happy when their brother came home with food.
After a three year time skip, they were shown to be living prosperously with Alain in a new home. They were not shown afterwards, however, Alain was shown in the fourth-to-last episode, guiding the now grown up Cosette (alongside Gavroche and Chou Chou), around Montrueil-sur-Mer as the stand-in Mayor, and recounting Fantine's story to the trio alongside Sister Simplice.