The Son

Olivier is a carpentry trainer in a social reintegration center. One day, the headmistress asks him to take in Francis, a teenager who wants to learn the woodworking trades. Olivier refuses, claiming that he already has too many apprentices. The young boy is then placed in the welding shop.
Who is Francis? Why does Olivier start to follow him in the corridors of the establishment, in the streets of the city, up to his building? Why is he so attracted to him? And why does he seem to fear it so much?