Lion - The lion is considered and said to be the King of the Jungle. Despite the fact that he is only the largest member of the cat family, the lion deserves the title due to his majestic appearance and position as top predator.
Being a gangster is a commitment to those people that you would "ride or die" for. Gangster will not stop until the deed is done. This relates to the book Monster because this is the lifestyle that Sanyika Shakur aka Monster Kody Scott decided to live.