David "questions"?

⁸ “But what have I done?” asked David. “What have you found against your servant from the day I came to you until now? Why can’t I go and fight against the enemies of my lord the king?”
⁹ Achish answered, “I know that you have been as pleasing in my eyes as an angel of God; nevertheless, the Philistine commanders have said, ‘He must not go up with us into battle.’ ¹⁰ Now get up early, along with your master’s servants who have come with you, and leave in the morning as soon as it is light.”
¹¹ So David and his men got up early in the morning to go back to the land of the Philistines, and the Philistines went up to Jezreel.

 David wanted to fight with the Philistines. As for why he thought that, that is another question. Why he wanted to just go out with them and fight? The Philistines are fighting against the Israelites. But, what was David thinking? David betraying God? No. He was God's secret agent in this land. He was "hidden" in the midst of Philistines and when the time comes, come out and bring God glory. It was not mentioned that David wanted to participated the war just to kill Philistines, neither did it say that David wanted to kill his own people. But after being rejected by the Philistines' elders, he seemed genuinely disappointed that he could not join the war. David is still a man of God dispute all these. We know that, that David lives on God's grace and mercy and on nothing else. That is the reason why he can survive this tough times. It is only God. Interesting point to note that Achish the Philistine mentioned God. God with a CAPS G. Funny thing huh. Maybe David spoke life into him, who knows.