"Our ambition in making this film is to see the harshness, the cruelty of the relationships of domination," say the Dardenne brothers Jean-Pierre and Luc, who have already won two Palmes d'Or and are back in Cannes with "Tori and Lokita," a drama in the form of a plea for migrant children. It is one of 21 films competing for the festival's Palme d'Or top prize. IMAGES AND SOUNDBITES