Oryx and Crake - Characters

pages  264/431
Hello all,
for my book project, I have been reading the book Oryx and Crake, by Margaret Atwood, a profound Canadian author.
I am currently on page 264.
This book is slightly different to most/all of the other books I have read. Despite the fact that recently I have been reading a lot of dystopian fiction, it was all YA. This book was written for an older audience, I believe, but I am actually enjoying it.
The main character in this book is Snowman, who, in his youth, was called Jimmy. He lives naked, all but a blanket and resides in a tree, eating mangoes and fish once a week. Now, to explain Jimmy/Snowman's situation, I will have to bring in the antagonist, Crake.
In Jimmy's childhood, Glenn and Jimmy were best friends, as they both lived in the compound where their parents worked, creating pigoons and other such genetically modified animals. They give each other nicknames, and Jimmy calls Glenn, Crake, a name that sticks for life. Jimmy, though, is called Jimmy throughout his life until he decides to change it in old age. The two of them are firm friends, playing chess and messing around online and watching films... and some of a not entirely appropriate nature.
To be honest, I think Crake is a sociopath. He values logic and he understands knowledge and is amazing at chess, yet he doesn't do very well at empathy or sympathy. Even though he isn't the greatest person to choose for a friend, they get along, and stay friends throughout their lives.
 Despite his problems, Crake gets wonderful grades and gets into the best university of his time. Here, he learns a lot about genetics and tissue and materials and so forth. Arm in arm with his knowledge, and lack of any sort of sympathy or feeling for others, he annihilates the human race with a disease of his making, and replaces all humans with his own genetically perfect human beings, with different tissues and genetic material from other animals. The whole human race is killed.
Wel... all except for Jimmy :) Now you see, Crake has left Jimmy, the last specimen of the human race, ever, taking care of the 'people of Crake', a group of 'perfect' human beings, although people who have no real knowledge or understanding of anything. They just act like Crake programmed them to, and like the animals that they have genetic material from. Jimmy has to look over and after them, and keep himself barely alive. He is permitted to one fish a week. The rest, he has to find and scavenge for himself. He has basically given up on life, and spends his time recollecting the past. He is somewhat determined, and lives each day trying to survive, but there is nothing left he can do. So he basically just waiting for death.
Thank you for reading,
Gemma