He is called Martin Prunevaux.

He asked me all manner of impertinent questions, and, if he fall in with you, may ask you as many; but remember Jaques Coeur's motto, "'En close bouche N'entre mouche--' "And again, 'Dire, faire, taire.'" "Ay, ay, father, you may depend on me," said I, heartily.
Sometimes, before I went to bed, I stepped out to get a glimpse of the light in Madeleine's window.

I should observe, it was also Gabrielle's, for the sisters shared the same room.

The moon cast strong lights and shadows, and I kept in the shade till close to the house, when what was my disgust to hear the wretched tinkle of a guitar under the window! Serenades might be all very well for Italy, but we did not favor them in Nismes; and stepping briskly up to the musician, I said abruptly, "We want none of this miserable noise!" He started as if shot, saying, "Pardon, monsieur," evidently taking me for one of the family; a mistake which I favored by knocking at the door.

As I was in deep shadow he did not recognize me, but the moonlight fell full on his face, and I saw it was Martin Prunevaux.