What does 2 Samuel 13:27 mean?

Amnon, David's oldest son, fell into a deep, dangerous infatuation with his half-sister, David's daughter Tamar. With help from a cunning cousin, Amnon convinced David to send Tamar to his house. Once they were alone, Amnon raped her. Immediately, lust turned to disgust, and he sent Tamar away, piling so much dishonor on her that she can never socially recover (2 Samuel 13:1–19).

Now, David's faced with another request to send one of his children at the request of another. This time, he asks more questions. His third son, Absalom, has asked David and his servants to celebrate with him in Ephraim while Absalom's workers shear his sheep. David declines, pointing out that that would take a lot of money. Absalom proposes that David send Amnon, instead. As the firstborn, he could represent the king (2 Samuel 13:24–26).

This should have raised David's battle-trained sense of danger. On the surface, it's a reasonable request. But Absalom is Tamar's brother. For the last two years, he's said next to nothing to Amnon. Why would he want to get together now, far from Jerusalem, amid his servants, with the man who raped his sister?

David challenges Absalom's request, and Absalom pivots. He suggests that all the princes come. We can't know what David is thinking. If he suspects anything, he might assume Absalom wouldn't have the chance for violence with that many people around: by his life's end, David has nineteen sons. As is the case in much of David's latter life, he acts without proper caution. He agrees and sends the group.

Absalom tells his servants to get Amnon drunk. When Absalom gives the signal, they are to kill Amnon. They do so, and Absalom flees, believing Tamar's honor is avenged (2 Samuel 13:28–29, 37).