David may be part of the family now, and Jonathan and Michal both love him, but Saul definitely doesn’t share their sentiments. “And Saul spoke to Jonathan his son and to all his servants to put David to death. But Jonathan, Saul’s son, desired David very much (Samuel I 19:1).” Love has now changed to desire, which has lead to many midrashim that speculate that Jonathan and David had an affair. Jonathan, at least, seems to love David in a less than platonic manner, and he ends up being loyal to him over his father. He tries to persuade Saul not to kill David, and he succeeds, at least temporarily. “And Jonathan called David, and Jonathan told him all these things. And Jonathan brought David to Saul, and he was before him as yesterday and before (Samuel I 19:7).” Things get back to normal for the moment, with David back in the fold and David fighting the Philistines.
The temporary truce doesn’t last. “And Saul attempted to pin David to the wall with the spear, but he slipped away from before Saul, and Saul drove the spear into the wall, but David fled and escaped on that night (Samuel I 19:10).” Saul is on a mission to kill David again, but by now it’s not only Jonathan who has sided with him. Michal, his wife, helps him escape through a window, and distracts her father while he runs away. “And Saul said to Michal, ‘Why have you thus deceived me, and you sent away my enemy, so that he escaped?’ And Michal said to Saul, ‘He said to me, ‘Let me go. Why should I put you to death (Samuel I 19:17)?”” Michal isn’t being fully truthful according to the text, but it makes sense that she wouldn’t explicitly tell her father that she had defied him only to save his perceived enemy.
David runs away, and goes to Samuel. Saul tries to get him back, but so far he doesn’t succeed. I can’t help but feel sad for Michal in all of this, caught between her husband and her father, and left behind to defend David as he runs away.