Cedric never stood a chance against Merlin and Arthur. Not when they are literally two sides of the same coin, bound by destiny, and especially not when they're secretly dating and trust each other with everything. Or-Cedric doesn't notice Merlin in Arthur's bed when he goes to steal Arthur's keys in the middle of the night, and that's his undoing. So no. He never stood a chance. Set in the episode 2x01 The Curse of Cornelius Sigan.