The family unit is perhaps the most frequently recurring motif in the Torah. From the first story of Genesis to the most recent supplementary texts of the Mishnah, everything comes down to fathers, mothers, sisters and brothers. At every turn, the greatest joys are those that focus on the simple triumphs of kin while the darkest tragedies are stories of when families fall apart. For King David, the loss of his crown or his country would not hurt as much as the systematic destruction of his family. Following his sin with Bath-Sheba, his punishments all revolve around losses within his own house.
Chapter 12 of Second Samuel begins with the prophet Nathan visiting David. Nathan tells David a sort of fable about two men, one rich and one poor. The rich man has a large flock to his name while the poor man has only one ewe he tends lovingly. When a traveler comes through town, the rich man opts to use the poor man's ewe to feed and clothe his guest rather than provide from his own sizable assets. David, being so completely trapped in the mindset of a leader, takes the story literally and demands justice. Nathan then explains that, as far as God is concerned, David is like the rich man. He had more than any man in his nation, but he greedily snatched another man's meager portion, if only because he could. For killing Uriah and taking Bath-Sheba to be his wife, for destroying the sanctity of family, David calls down ruin on his own family.
The first strike against David is the loss of the child he conceived with Bath-Sheba. Only seven days after birth, the child dies of illness. There's a very interesting turn in these passages. While the child is sick, David fasts and sleeps on the ground, but when the child dies he resumes eating and returns to his house. He explains to his advisors that the penance was an attempt to appease God. Now that the child is dead, he has no reason to suffer. This paints David both as a pragmatist and as a man who has a surprisingly conversational relationship with God. There's an emotional emptiness to him after this episode, a sense that he is a man who shifts between agony and numbness.
It is that same numbness that compels David to order the murder of one of his own sons in chapter 13. Amnon, David's oldest son, conspires to rape his half-sister Tamar. After the deed is done, word gets back to David and he sets events in motion to end in Amnon's death. Following the killing, David receives false word that all of his sons have been killed. The symbolism of this tragedy is clear. Amnon is the heir to David's now-tainted throne. Like his father, Amnon gives in to the basest of his sexual proclivities and causes irreparable harm to his family in the process. All the same, by condemning one of his sons, David symbolically condemns them all. Like Saul before him, David attempts to do God's job. Though Amnon deserved death under the law, he never even stood trial. He was cut down, alone in the wilderness. A strand of that old chaos from the previous throne is in this episode. Order gives way to the caprice of kings, brothers set upon brothers and the lines between right and wrong blur until they lose all meaning.