i've got red in my ledger (джен)

Out of instinct honed by a decade of battle and split-second decisions, Arthur whirls around, and is promptly faced with the sight of Merlin—Merlin, who trips over about ten things an hour and cannot lie to save his life and has proven his loyalty to Arthur in a thousand different ways—thrusting the ceremonial sword towards Arthur’s chest.
The very air seems to have stilled.
 
Or: Merlin tries to kill Arthur, courtesy of the Fomorrah, and this time, Gwen and Gaius don't get to Merlin soon enough to knock him out.
[written for whumptober day 5: betrayal | misunderstanding | broken nose]