What are some examples of loyalty or disloyalty in the book?

Loyalty and brotherhood are major themes in this story. Bryon even says so explicitly at the very beginning of the story while he was describing their appearances: “He was my best friend and we were like brothers” (pg. 13). When Mike in the hospital mistakes them for being actual brothers, Bryon does not bother to correct him, and says that even “For a minute I really felt good about Mark’s telling this guy we were brother” (pg. 33). Bryon feels not only a pride in being “related” to Mark specifically, but also a security in being bound to another person in such an intimate fraternal relationship. Bryon and Mark try to figure out and understand this feeling and how it has worn off over the years with their other friends: “We were like brothers, not just you and me, but all of us together. We woulda died for each other then. And now everybody’s kinda slipped away, and then we woulda died for each other. Really, man, remember? It was great, we were like a bunch of people makin’ up one big person, like we totaled up to somethin’ when we were together” (pg. 68), says Mark. This explains the difference between brotherhood and other forms of friendship. ‘Being brothers’ means being family, and Bryon’s eventual riddance of Mark is like ridding himself of a body part.