Author's Note: This was edited as of 2/28/16 for slight grammar corrections.
Francis's actions are caused by his desire for independence. To be himself free from the shackles, expectations that his mother has made. To prove to his parents, especially his mother, that he can strive and live without them. He is ignorant on how his actions affect his little brothers who look up to him. He views brothers as special and unique, this blinds me to what lies behind surface.
It should be no surprised that Reese's actions are caused by fury. The cause of the fury would be a surprise though. His conflict with his brothers is caused by his mother, which something she never realizes. He is angry at Francis who abandoned them to her whim. He is angry at Malcolm for mom pays special attention to him; after all he has a plan set out for his life. He is angry at Dewey for being the cute and special one. He's even angry at Jamie, for being the youngest. The person who Reese is most angry with is not his mother, it is his father. A father who allows his wife to control their sons, this above all of else, the fact that he did nothing to stop her makes Reese hate his father with such an intensity that rivals the sun.
Everybody would be horrified and surprised on what drove Malcolm. Malcolm's actions are caused by one and only one thing: hatred. He hates Francis for not being there to guide him as an older brother should. He hates Reese for picking on him and not guiding him like an older brother should of. He hates Dewey and Jamie for the same reason: they needed to be protected and guided, this hate is unique is that it is caused by the fear that he will fail to protect his little brothers. He even hates father for not realizing that he was falling into the maw of hatred. He hates his mother with such a burning fiery passion for controlling his life. The most disturbing thing is that the one he hates the most is himself. He hates himself for being consumed by hatred, failing his younger brothers, not being able to forgive older brothers, for looking so much like the father that failed him, and for being such so desperate for his mother's love, that he agreed to live out her plan for his life.
Dewey's actions are caused by the desire of protection. Since he was ignored, picked on, or tricked by older brothers he vows to treat any younger siblings he gains as equals. He blames both his parents for the way his life has treated out. Especially considering that he only has vague memories of his early life, memories that his parents failed to keep. He protects and treats his younger older Jamie as an equal.
Jamie's actions are caused by his desire to have a family that spends time with one another. He wants the attention of the Francis, who rarely if ever visits. He wants to be able to play with Reese and stop him from being so angry. He wants to be around Malcolm, if only to get his mysterious and distant older, brother to smile. He loves being around Dewey for that is when he believes his dream of keeping the family together will come true. He wants to understand his parents, but finds them to be weird.
Unknown to the boys, their father sees all. Hal's actions are caused by his cowardice. He is a coward that is afraid of pushing Francis away and out of their lives by making him realizing that moving so far away is not a good idea. He is afraid to confront Reese, who becomes angrier and angrier by the day. He is too horrified by the self-hate within Malcolm's eyes to try to save him from the abyss. He's cowardice and guilt prevent from talking to Dewey about how truly sorry he is for not saving him memories. He sees Jamie's desire and never tries to help the dream become a reality, for he is afraid of pushing away his children further away from him. Hal hates himself for being too much of a coward to stop his wife from controlling their children.
Lois's actions are caused by her wants and desires. She wants Francis to quickly get a job and grow up fast and quickly. She desires for Reese to be better, smarter, and she can't bring herself to accept him for just how he is. She expects, demands, that Malcolm become president. She believes that Dewey would make a good scholar. She wants Jamie to be a teacher. Her wake up call will be terrible.
Francis is strong, but unfortunately he fails in protecting his wife and kids from the beast of the abyss. Reese is too stunned and fury fails him when he is killed in cold blood by vengeance itself. It is Jamie who answers the door and is too excited by the smile to notice that is something is terrible wrong, until the knife is stabbed into his stomach. Dewey will rush to protect, only to freeze in horror as his own flesh and blood looks at him and then slices his own throat with the knife used to kill Jamie. A sword is drawn and Hal screams when the blade pierces his heart, before death claims him, Hal will gaze into eyes full of self-hatred. Lois is thrown into a wall and breaks her back, and in her final monuments Lois gazes upon a monster that she crafted by playing god.
Hatred is a poison that twists and bends a person into gaining vengeance. Malcolm Parker Wilkerson is gone and only Vengeance remains.