Seven Days with Joab

Whatever became of Joab, renegade commander of King David's army?
Amidst wars, murders and jealousies, the story of Joab weaves in and out, always intertwined with King David's dysfunctional family. King David followed God and that was partly why Joab followed David. He could see the victories and blessings God showered on David. He wanted a piece of that. He'd also heard that the women adored David. They sang, "King Saul has killed his thousands, David his ten thousands." So, Joab joined David's rag-tag band of followers.
David noticed him. But Joab had a strong personality - headstrong, vindictive, sometimes overzealous. He liked to make his own rules, be his own God, his own judge and jury. In Joab's eyes, David took too long to act and wasn't always fair. Joab could easily see what needed to be done. Family was important, but the enemy was the enemy - no truce, no honor.
So, when did hero worship turn to disdain? Why is Joab called the Judas of the Old Testament?
Joab learned that David wasn't as moral as he had thought. Joab had his own sense of morality buried deep inside his pride. When David involved Joab in his own sin, not once but twice, Joab felt his influence eroding. He could only stand by and watch David and his God battle out the consequences of sin.
As David got older, his body became weak. Joab was still strong. He could foresee a vacuum in the affairs of state. Joab knew that the old king needed to be replaced. What action should he take?