Thamar
King David's eldest son Amnon, who was heir to the throne, passionately lusted after his stepsister Thamar. A girl of great beauty, Thamar lived with her mother at the royal court of David, although in different quarters than David's other wives, concubines, and serving girls. Following the suggestion of a friend that he should seduce the girl, Amnon pretended he was ill and needed medical attention. When his father visited him, he entreated the king to let Thamar nurse him back to health. So the king sent for Thamar to make Amnon some food and to feed it to him. once alone with Thamar, Amnon gave vent to his lustful desire. He said to her, “Come lie with me, my sister.” Thamar rebuffed him, saying, “…do not force me; for no such thing ought to be done in Israel: do not thou this folly.” She attempted to dissuade him, pointing out that he would be committing an ungodly and foolish act. Then she appealed to his sense of honor over the shame she would have to bear: “And I, whither shall I cause my shame to go?” But Amnon could not control himself; he “…forced her, and lay with her” (2 Samuel 13:11–14).
However, after he had made his conquest, her presence was a constant reminder of his wrongdoing, so he sent her away. Thamar, engulfed in bitter sorrow and probably weeping, encountered her brother Absalom, who coaxed the horrible truth out of her. The king was informed of the unfortunate incident, but levied no chastisement or punishment on his impulsive heir.
Why didn't David hold his son accountable for the rape of Thamar?
The Bible does not answer that question. The speculative answer might be that perhaps he believed that he and his son were accountable only to God. A powerful and popular king, David was a polygamist with numerous wives and concubines. He committed adultery with Bathsheba, and when she became pregnant, he ordered the murder of her husband.
Absalom took his sister into his home and began to formulate a plan of revenge. He didn't show any outward sign of his anger, but his hatred of Amnon and disrespect for his father festered inside him. For years he waited to avenge his sister, and when the timing was right, he meant to slay Amnon and seize the throne from his father.
Absalom's plan finally began to come together during the annual sheep-shearing festival. There would be the customary first clip of the flocks to be given to the priest, and then a great feast to follow. David sent Amnon to attend the festival in his place. When Amnon had drunk too much wine, Absalom's men overpowered and killed him.
Hearing the dreadful news, David banished Absalom from his court. Absalom used the time away to rally forces in his favor, and to incite discontent with the rule of his father. Then, he found means to return to the good graces of David, all the while secretly plotting to seize the throne. His attempts at a coup failed, however, and Absalom perished.
Absalom was said to be the most beautiful man in David's kingdom. His hair was heavy, luxuriant, and long, but a liability when, during the battle with David's forces in the wood of Ephraim, Absalom's hair became entangled in the branches of an oak tree. As he struggled to extricate himself, his father's general, Joab, thrust three spears through Absalom's chest, instantly killing him.
The Bible says David deeply mourned the loss of his son, and erected a mound of stones at the place where he died. No further mentions are made of Thamar, though it is likely that she, too, mourned the loss of Absalom, the one honorable man who stood up for her.

