Lawrence Boadt provides this summary of 2 Samuel….
The Book of 2 Samuel centers on the reign of David. It can be divided into two parts. Chapters 1-8 show how he managed to consolidate power in his own hands and to win a large empire for the newly united Israel. Chapters 9-20 record the downfall of many of his hopes as struggles in his own family weaken his reign. It is the story of how his sons fight to become his successor on the throne. Much of the tragic outcome develops from David’s own sin.
The rise of David to power showed that he was both a military and a political genius. He defeated his Philistine masters and extended the borders of Israel across all the small states of Syria and Transjordan. He could really be said to rule from the “river of Egypt to the Euphrates” (Gen 15:18; Jos 1:4). Thus the dreams of Israel were fulfilled in David. But even greater than his military conquests was his gift of winning over others to his cause. He had won the loyalty of the south by showering them with benefits while nominally a servant of the Philistines, and was crowned king of Judah at Hebron shortly after Saul’s death. He then patiently maneuvered and waited for the collapse of the badly run remnant of a state set up by Saul’s surviving son, Ishbaal. 2 Samuel 3:1 expresses this period succinctly, “There followed a long war between the house of Saul and the house of David, in which David grew stronger and the house of Saul weaker.” Finally, Ishbaal’s general, Abner, turned traitor and joined David, Ishbaal was killed, and the northern tribes came to Hebron and offered to make David their king also. The fact that he became king by mutual agreement was very important in the centuries ahead since he took the throne not by right nor by conquest, but by the free consent of these tribes. Later they would withdraw from his kingdom and form an independent state.
2 Samuel 1 provides an alternative account of the death of Saul from that which we read yesterday in 1 Samuel 31. In this second account, Saul dies at his own request but by the hand of an Amalekite, rather than directly by his own hand. These two accounts obviously come from different sources.
2 Samuel 2:1 highlights the character quality of David that sets him apart from Saul. Once again, “David inquired of the Lord…”
2 Samuel 3 tells us of six sons born to David by six different wives. As Richard Elliott Friedman says, David was a lusty man. When we get to the story of David and Bathsheba it will be no surprise that David desires her. David’s sexual relationship with Bathsheba is not the problem, from the perspective of the author(s) of this book. The problem is that David literally steals Bathsheba from another man and then kills that man. We must remember that women at this time were viewed as property and that part of what David was doing by taking so many wives was that he was forming alliances. The fact that he married the daughter of King Talmai of Geshur (2 Samuel 3:3) is an example of this.
2 Samuel 4 recounts the end of the house of Saul, something that fills David with no pleasure whatsoever. In fact, out of loyalty to Saul’s house, David has the murderers of Saul’s son, Ishbaal, executed and publicly hung, while Ishbaal is buried more appropriately in the tomb of Abner at Hebron, near David’s headquarters.
In the midst of all the ups and downs, ins and outs, good and evil, of David's rise to power and reign, the key thing is that he "inquired of the Lord". He sought the Lord's input on the direction of his life. David did not always follow God perfectly, but at least he kept God in view most of the time. The question is: do we?