8. Ned Not Telling Robert About Joffrey's Parentage
By following the trail of clues left by Jon Arryn, the previous Hand of the King, Ned is finally able to deduce that Joffrey, Tommen and Myrcella Baratheon are actually not Baratheons at all but the children of an incestuous relationship between Cersei and Jaime. Ned has every intention of alerting Robert to this fact upon his return from his hunting trip. Unfortunately, Robert is mortally wounded by a boar and is near death upon his return to King's Landing. Ned decides to let his king and friend die in peace rather than reveal the truth to him in his dying moments. Ned made a lot of mistakes while playing the game of thrones but you've got to think that telling Robert the truth right then and there was one of his gravest mistakes. Robert would have become infuriated and gathered the strength to order the immediate executions of Cersei, Jaime, and probably even his children. Perhaps that would not have been fair to Tommen and Myrcella (Joffrey, he could've executed and we wouldn't have minded one bit) who didn't ask to be the children of incest. Of course, this is a moot point since Ned had warned Cersei to flee the city with her children (and I'm certain, he actually expected her to do so). Ned probably knew that Robert's wrath would be severe and that he wound find them nonetheless, but surely the death of a few traitors would be preferable to the countless deaths caused by the ensuing War of Five Kings. Ned could have averted that all with the truth.