The Thief (movie, 1997)

In 1946, a soldier fathers a child then dies before its birth. Jump to 1952: on a train, the child and his mother meet a handsome soldier who makes a play for her. She accepts. Posing as a married family, the soldier finds them a rooming house where he becomes everyone's favorite through his good looks and generosity. Meanwhile he gives the boy, Sanya, lessons in life: to fight back, to win at all costs. The child's mother, Katya, is head-over-heels in love with Tolyan, the soldier, but the relationship becomes rocky when Tolyan's true plans for the rooming house become clear. It starts them on a treadmill of flight that risks Katya's life, Tolyan's liberty, and Sanya's trust.