After shooting Marc repeatedly he is still not down and the more times he shoots him Marc comes closer to him and when he reaches him he hugs him and apologies to him. He even calles him a name he never told about and when he said Damien he known it was his name.
(the reason he was shooting at him because after the world ended Marc ran off leaving everyone to die and leaving Melissa with a baby, and after she died the baby was left to hate his father for leaving. When Marc learned this information about his future he now must find a way to prevent it from happening)