I know that there are really good and accepted theories and reasons for the names in the movie, but I always thought Arthur was meant for King Arthur who joined Lancelot (Cobb) on his quest for the Holy Grail (redemption) but Lancelot’s love for Gwenevere (Mal) led him to betray Arthur time and again, (like how the projection of Mal is dangerous to the group, but especially to Arthur) so Arthur has to battle Lancelot. (like when they argue about Saito dying in level one) During his quest, Arthur calls upon the magician Merlin (either Miles, or Yusuf) and Lancelot’s son Galahad (Ariadne) who was more noble and a better knight than his father (Ariadne was described by Miles as a better architect than Cobb, and even asked if he was going to corrupt her, like how Galahad was tempted to be a lesser Knight by the legend of his father) Robert Fischer is The Fisher King whose empire suffered due to great wounding to himself, that wound came when he married a woman whom the Grail had not chosen for him (Robert was being wounded by not following his own path, but by trying to keep his fathers legacy going, so opposite, but similar) Parcival could be Browning, The Fisher King’s nephew, whom The Fisher King was assigned to so he could aid in the Grail quest to keep Parcival on the right track, but to never fully intervene with Parcival’s destiny.