Demetrio's character is developed mainly through his speech and the influence it has on his crew, illustrating his leadership qualities.
The author develops the character of Demetrio in the excerpt from "The Underdogs" by Mariano Azuela primarily through his speech and actions. The question mentions Demetrio speaking to his crew, scrutinizing their faces, and recalling past events where few men overcame greater numbers. This showcases Demetrio's leadership and wisdom. Although his actions aren't directly narrated in this passage, the response and the eagerness of the crew to follow his lead are testament to the respect and influence his actions have earned him over time.