Final answer:
Meir Katz saves Elie by stopping an attack on him; surprisingly, despite his strength, Katz stays on the train due to despair.
Step-by-step explanation:
In the context of the historical novel Night by Elie Wiesel, Meir Katz saves Elie's life by preventing him from being strangled during a disturbing event on a train transport. The surprising aspect about Meir Katz's decision not to get off the train lies in his role as a robust and helpful figure throughout the journey, which comes to a devastating conclusion as he succumbs to despair and can no longer find the strength to continue the struggle for survival, despite having been a source of support and life-saving actions earlier.