In the list of David's sons born during the sojourn in Hebron (verses 2-5), the reader identifies the chief figures who will darken the later story of David: Ammon, who will rape his sister; Absalom, who will rebel against David himself; and Adonijah, who will attempt to steal the throne in the closing days of David's life.
The story of Abner's defection to the throne of David (verses 6-21) describes how the northern and southern kingdoms become united. As a royal relative and the recognized commander of Israel's army, Abner's responsibilities are considerably increased after the death of Saul and Jonathan at the Battle of Mount Gilboa. Indeed, the political stability of the northern tribes greatly depends on his personal authority during these troubled years, nor could the house of Saul have stayed in power, up till now, were it not for the backing of Abner.
Following the Battle of Mount Gilboa, the Israelites are divided between north and south, a division rendering it easy for the Philistines effectively to control most of the northern area west of the Jordan. This hapless situation, threatening to become permanent, poses for Abner a true moral dilemma.
He is an instinctively loyal man, principled, and innocent of personal ambition. The sundry loyalties of even such a man, nonetheless, may sometimes stand in conflict, and Abner is compelled in due course to choose between his expected adherence to the house of Saul and his more abiding concern for Israel's very survival.
Long accustomed to viewing David through the eyes of Saul, Abner experiences much of the same conflict of loyalties that earlier plagued the conscience of Jonathan, and his painful resolution to that conflict, like Jonathan's, leads directly to the tragedy that ends his life.
The story of Abner's murder by the hand of Joab (verses 22-30) is tied directly to the previous chapter, where Joab's brother, Asahel, perished at the hand of Abner. The contrast between Joab and Abner could not be starker. Joab is a simple and savage character, whose actions often gain no credit for the throne of David. Here he murders Abner in cold blood, insouciant to the reputation of David, who offered Abner political refuge. Later, he will murder the defenseless Absalom.
In the final account in this chapter (verses 31-39), we find the exasperated David lamenting the murder of Abner but politically unable to execute justice on the murderer. He does, however, go to some length to separate himself from the deed.