“A mistake is an event, the full benefit of which we have not come to realize.” (Unknown) Something that was not initially meant to happen can shape those involved for better or for worse in the future. In The Once and Future King, the slippery trail that leads to one of King Arthur (the protagonist’s) greatest mistakes starts with a fault in someone else entirely. While Arthur is planning a wedding, Merlyn, Arthur’s teacher, remembers what he has forgotten to tell Arthur earlier. Long story short, Merlyn forgot to tell him that Morgause is Arthur’s half-sister, and the characters Gawaine, Agravaine, Gaheris, and Gareth are his nephews.…