Why did Soda send a letter with Dally?

Soda sent a letter with Dally to deliver a message to their brother, Ponyboy, during a crucial moment in the story. Soda wanted to communicate his feelings and help bridge the emotional gap that had formed between Ponyboy and Darry. By sending Dally, who was more familiar with Ponyboy's situation, Soda hoped to ensure the message was received in a way that would resonate with Ponyboy. This act underscores the theme of brotherhood and the importance of communication in their relationships.