Any synopsis about Matt Fowley from "Killings" should address how he loves his family. Matt is devoted to his family. Their happiness and safety ate the most important elements for him. There has been an almost insulated element to the Fowleys' condition over time. They have been able to deal with most of what life has placed in front of them. Matt and his family are shattered when Frank is killed and Richard is viewed as an outsider, an intruder who disrupted this familial construction.
Frank's death is what causes Matt great pain. It moves his otherwise steady moral compass to an unimaginable end. Matt's desire for vengeance is rooted in how he feels that he has failed to protect his son. The anguish echoed by his wife are elements embedded within him. It is this descent into a moral abyss that defines his characterization as the narrative progresses. Lacking an effective means to understand grief, a loving and dutiful father is consumed to a point where murder is both premeditated and embraced. To see Matt descend into such a condition is a significant part of his characterization.