How are some of the characters identities constructed by there past and present experiences?( 2 characters at least would be great!)

Glenn, renamed Crake during the playing of Extinctathon, is Jimmy's peer and best friend. He is a brilliant student and spends most of his time living in a world of ideas. After high school, he attends the prestigious Watson-Crick Institute where he buds into a formidable geneticist. His talents in this field as well as his unique philosophies ultimately lead to his creation of a group of humanoids later referred to as the Crakers. Over the course of the novel, Crake turns from boy to brilliant teenager to mad scientist. His past life of disposable morality and detachment from society shapes his Armageddon-like approach to revamping the genetic makeup of the world.