Here we discover that Prince Jonathan became David's closest friend... but, King Saul became his worst enemy. At first David was viewed by Saul as a wonderful contributor to his court. Saul even exalted him to a high rank in his military, but it didn't last. When it became obvious that David’s popularity and ability had surpassed the king's - David became a target of Saul's insane and violent jealousy. Although Saul didn't know factually that David had been selected as his replacement, the suspicion of it flowed over Saul like a flood. Twice Saul attempted to kill David while David was in his presence serving him. So, Saul sent him out of his court into a field position as the captain over 1,000 soldiers. But, even there David's popularity grew... as did Saul's fear of him.
If I had to pick a favorite incident from this scene it would have to be the development of the friendship between David and Jonathan. I Samuel 18:4 paints a powerful portrait of brotherly love as it describes how Jonathan took off his fine royal military uniform and gave it to David to wear. It was very symbolic of the reality of what God was really doing in Israel at that time.