Episode 2 - Merlin Season 5

That's the true bane of Arthur: not Mordred. But Merlin's helpless love. If you'd like, I can also trace how this episode sets up specific plot threads for the rest of Season 5 (Mordred's love interest Kara, the Disir, Camlann). Just let me know.

This episode plants the seed: Arthur says to Mordred, "You've proven yourself a true knight of Camelot." Merlin watches, helpless. The tighter Arthur and Mordred bond, the more inevitable the dagger in the back. Morgana reappears as a broken, hate-filled shadow. She's no longer fighting for the throne — she's just destroying. She captures Arthur not for a grand plan but for pure revenge. merlin season 5 episode 2

This is noble. But the show argues that in a world of prophecy and magic, nobility can be fatal. Arthur dies not because he's cruel, but because he's good. His faith in people is exploited by destiny itself. That's the true bane of Arthur: not Mordred