The fact that Odysseus had his crew tie him up as they passed by the Sirens reveals a lot about his character. Firstly, it shows that he is aware of his own weaknesses and is willing to take measures to prevent himself from succumbing to temptation. The Sirens were known to lure sailors with their enchanting songs, causing them to steer towards the rocks and their doom. By having himself tied up, Odysseus was ensuring that he would not be able to give in to the temptation of their songs and put his crew in danger.
Secondly, it demonstrates Odysseus' cleverness and strategic thinking. Rather than simply relying on his own willpower to resist the Sirens' call, he came up with a plan to neutralize their threat altogether. This not only protected his crew, but also allowed him to experience something that no other mortal had - the Sirens' song - without suffering the consequences.
Finally, it shows Odysseus' leadership and authority over his crew. Despite his desire to hear the Sirens' song, he recognized the danger it posed to his men and took steps to protect them. His crew obeyed his orders without question, demonstrating their trust in him as their leader.