Arlette Laguiller: she represents a sectarian, secretive Trotskyist party called Lutte Ouvrière. But she's a popular figure in France. She has been a candidate at every presidential since 1974. Her image is: she used to be a bank clerk, she's a nice, ordinary, reassuring working-to-lower-middle-class Frenchwoman who may well still drive around in a Deux Chevaux or on a moped.

José Bové is another very popular leftie. His stand on food quality speaks to (many) French hearts. If the main parties had people of the charisma and capabilities of Bové instead of the horror show they've actually got, they'd clean up.

Mélenchon (not to be confused with Melanchthon ;)) is on the left of the PS, a main figure in the "non" movement with Fabius.

The changes in sympathy, I don't know, except that, at the moment with a social movement under way, the main parties lose points that the fringes pick up (? conjecture).