Not quite dark ages, but I would like to know more about Edward the confessor. He's one of those historical figures that no historian agrees about. Was he a competent king who was overshadowed by Harold Godwinson, a weak and ineffective ruler but a also a nice guy who was trying his best, a weak and ineffective ruler but also a petty tyrant who was willing to let England metaphorically burn out of spite and who always sided with foreigners, or was he actually completely disinterested in ruling and let everything in the hands of the Godwin family and the rest of his advisors while he worked on Westminster Abbey, some combination of all four? And there's also the question of whether he intended to leave England to William from the beginning, if he promised England to various people as a way to manipulate his rivals or as a desperate attempt at avoiding a war because it was his only diplomatic tool (this one goes in hand with the 'weak and ineffective' theory) or he never actually promised England to anyone and the various rulers who claim otherwise (Harold, William, the king of Denmark) are all lying. Plus what his relationship with Edith was actually like, and if he really poisoned his half-brother (I first saw this theory here and it seemed ridiculous but a historian interviewed in a BBC podcast about Edward believes it so who knows?).