David had sown his wild oats, and there came a time to harvest. David’s fields bore their wild grain in abundance. David's stubborn willingness to obtain what he desired by whatever means necessary was passed down to his children. Naturally, this was not a good thing. In this chapter, we find the infinitely sad story of David's son (Amnon) and his incestuous rape of his own sister, Tamar. Amnon passionately craved his sister (well, half-sister). He desired her physically with such intensity that it affected his health. And, unfortunately Amnon had a cousin named Jonadab who contrived a scheme by which Amnon could get what he wanted.
With Jonadab’s help and under the guise of needing a nurse, Amnon finagled his way into being alone with Tamar. Then he did his wicked deed and sent her away in shame. Perhaps the saddest part in this whole story is the perspective that Tamar had. II Samuel 13:13 indicates that she would have been willing to marry Amnon if he would have followed the proper cultural procedures of their day. Sadder still, she was willing to stay with him after he had forced himself upon her (11 Samuel 13:16), but his evil heart had turned and he suddenly hated the very thing that he had thought he loved.
Then in a vengeful reaction against Amnon, Tamar and Amnon's brother Absalom aimed to set matters straight. After 2 years of stewing, Absalom had all his brothers over for dinner and had Amnon killed while he was sitting at the table drinking.