The House of the Scorpion
by Nancy Farmer
Though he's a fairly competent doctor, Willum is a pretty awful person. He really has it in for Matt-the-clone, so he does the absolute bare minimum to keep Matt alive and functioning. Willum is very self-serving, too. We learn this when he throws Rosa under the bus to El Patrón, after the boss finds out that Matt has been held prisoner. It's a pretty despicable thing to do, because Willum is in a relationship with Rosa at this time. Even though Willum played a role in jailing Matt, he wiggles his way out of being punished for his actions. Then he sets his sights romancing Felicia. We won't go there.