What character does Holden feel most strongly about in Romeo and Juilet?

Holden Caulfield feels a particular affinity to the character Mercutio from Romeo and Juliet. Holden is a clever and witty narrator, always giving a wry observation or discussing sex and in this he is very much like Mercutio in personality and wit. Mercutio is dynamic and likable and it's no surprise Holden would identify with him.

In the scene when he brings this up, in Chapter 15 of the novel, Holden mentions that Mercutio's death was the one that bugged him the most, more so than Romeo's or Juliet's deaths.  He points out that Mercutio was not involved in the family feud or the love story and blames Romeo and his actions for Mercutio's death. Though Romeo and Juliet died as a direct result of their families and choices, Mercutio was an outsider, an innocent. Holden values innocence above all else – consider how he talks about his sister Phoebe – and so would naturally mourn the death of a character who had done nothing wrong. He sees Mercutio's death by Tybalt as similar to a child who is forced to grow up too fast, and mourns both.