What did Polyphemus do to keep Grover from unraveling the wedding train?

Polyphemus, the Cyclops from Greek mythology, kept Grover from unraveling the wedding train by using his immense strength and cunning. He tied Grover up and placed him in a position where he couldn't reach the wedding train, preventing him from sabotaging the event. Additionally, Polyphemus was protective of his prized possession, ensuring that no one interfered with his plans. This combination of physical restraint and vigilance effectively thwarted Grover's attempts to disrupt the wedding.