User blog comment:Broman178/How Arthur could have confronted Agravaine in the Series 4 finale./@comment-4190137-20120310041843

I think I like Part 1 better, but here's my theory.

In Part Two, Agravaine and his men are hunting Arthur in the tunnels. Then they confront, Arthur, Merlin, Gwen, Tristan & Isolde. Arthur argues with Agravaine at first, saying, "Why did you betray me Agravaine?" Agravaine replies, "Because your father betrayed me, by betraying Ygraine. He went to the sorceress Nimueh for help on concieving a child. It resulted in her death. And then he kills my brother, Tristan de Bois, who only seeked reason." Arthur, shocked, replies, "No! That's impossible, that didn't happen! You're lying!" Agravaine smirks and says, "Arthur, seach into your feeling, you know it's real. But you can join me. Together we can overthrown Morgana, and rule over every ruthless soul who has despised us." Arthur, still looking shocked, but tempted. Merlin butts in and says, "No Arthur!" Agravaine stares angrily at Merlin, "keep your filthy nose out of this you filthy servant. Arthur, don't listen to him, go towards reason." Arthur, now angry, looks up, "Never!" Then he attacks Agravine with his sword, Agravaine survives the first few blows but he eventually dodges one, and flees, leaving the Southrons to fight them. But Merlin goes after Agravaine. Then they have the conversation they had in the real thing... "Ohh you're Emrys!" And then Merlin kills Agravaine.

That's my alternate theory.