It had taken the Order long than they expect to find the train using their brooms. The group had spilt up to cover different sections of the train, hoping to corner the Death Eaters and minimize injuries to the children.
Sirius used his wand to blow a hole in the ceiling of one of the compartments. He dropped into the hole, yanked out his wand, and surveyed the area. A familiar looking blonde student was gawking at the hole in the ceiling. When he prepared to run, Sirius grabbed him by the back of his robes, threw him into the closest cabin, and hexed the door closed.
But the moment he spotted Bellatrix, his eyes narrowed and he began firing hexes in her direction. "Hello cousin!" he shouted. "We've got some unfinished business!"