Ishbaal is one of Saul's four sons and David's main rival to be the undisputed king of all Israel. Ishbaal puts up a good fight, at first—with the help of his general, Abner. But ultimately, he meets a messy and bloody end. Saul and his whole family, in the end, are cursed. If things start to look up for them, it means that's just the build-up before the inevitable, crushing defeat.
Ishbaal meets his own crushing defeat in combat with David. He has to give his own sister (Michal) back to David, to be his wife, and to make matters worse, he loses his general, Abner, to David as well. He's finally killed by a pair of ruffians, who cut off his head and bring it to David—who promptly kills the ruffians as punishment… Overall, the story of Ishbaal is just a big bummer.