New for me anyway. In list form because they aren't coherent yet.
1. 2 Samuel 9-12 is a discreet section. 2 Sam 8:15-18 reads like a conclusion to the previous section. The Ammonites are are Israel's enemy in this section. The battles against them begin in chapter 10 and they were finally defeated at the end of chapter 12.
2. 2 Sam 9 and 10 both contain very favourable accounts of David. David shows kindness (hesed) to Mephibosheth (9:1) and Hanun (10:1). The kindness that the Lord has shown to David (7:15, 9:3) is overflowing from David to others. Mephibosheth's reaction to this kindness ("What is your servant that you should regard a dead dog like me?" (9:8)) is similar to David's reaction to God's kindness ("Who am I O Lord ..." (7:18)) Hanun's reaction of suspicion and anger is quite the opposite and leads to the war against Ammon.
3. A good sign of whether we really understand the kindness that God has shown to us (in Jesus) is whether or not we pass it on to others. In chapters 9-10, David shows that he gets it. We need to accept God's kindness to us and show we understand it by passing it on to others.
4. Rejecting the kindness of God's king is dangerous. Hanun experienced the consequences of this.
5. In the whole sorry story of David and Bathsheba (2 Sam 11-12), David's sexual ethics are not the primary problem. The main problem is David's lack of kindness to Uriah. The lamb parable that Nathan tells shows that it is David's mercilessness that he is being judged for. God has given him so much, but David is no longer passing kindness on, he is taking from others. This is bad and stands in contrast to the last couple of chapters.