Merlin pushes Arthur out of the way just as the cave walls collapse in on them. He is slammed against the ground and pain shoots through his bones but he is up as soon as he is able, looking wildly for any sign of his (last) ally.
Only a trickle of light shines through, casting shadows on the rocks and he can’t see his warlock anywhere, “Merlin!” He shouts, his voice echoing off the stone and into the cold abyss waiting in front of them. “Merlin, where are you?”
There is a strangled noise from beside him, and Arthur turns, feeling his breath escape from him when he sees his skinny manservant, half swallowed by heavy rock.
They had been at war against Morgana, Mordred and yet another army of undead soldiers. Merlin, the court sorcerer held off the enemy forces with what magic he could while Arthur went for Mordred’s head.
He remembers that dark throne, placed on an altar made from bones of the fallen by the sadistic child. Remembers climbing up, prepared to kill the boy (for the sake of the greater good, for Albion, he recalls trying to justify to his honour) and then dropping his sword in shock when he sees that Morgana has already killed him.
Morgana, half dead herself, a dagger in her heart.
She is cackling, half in tears and half in mirth, when he comes near.
“...He upset the balance...” Morgana laughs, “And so I had to stop it, but it’s too late now... too late... too late... the gods are angry... we will be punished...”
“Morgana,” he holds her, “don’t. Stop,” he tells her, when he sees the blood bubbling from her lips, “stop talking.”
She does and she smiles weakly at him, cold fingertips brushing his cheek.
And then she’s gone.
“Wake up, talk to me, Merlin, say something, anything, be an idiot, just talk to me,” His fingers slip and draw more crimson again when he tries to lift more of the rubble off of his sorcerer’s body.
They’re trapped, with no way out at all.
“The last day of your life,” Merlin groans weakly, though they both know that it’s no joke at all, “What would you like to do?”
Arthur slumps down and clutches at his warlock’s (cold) hands, listens to his laboured breathing.
Outside the cave, the whispers in the night, the groans, grow louder. They’re coming.
The undead army had kept killing. Despite the loss of their leaders they advanced and no matter what spells Merlin cast, they would break them.
The villages were wiped out. Every man, woman and child killed slowly rose from the grave, joining the ranks of the army, destroying more lives.
Arthur did what he could to protect those outside of Camelot, but it came to the point where the castle was surrounded. Merlin had become too weak, inflicted with an illness that targeted all magic users. Most had died but Merlin stubbornly held on to life. He had to; Arthur would never forgive him if he didn’t.
“You should leave me,” Merlin says, when it is only Arthur, Gwaine and him left. (Gwen, gone the day that their defenses were broken, her dead eyes staring at them when she ripped apart Percival and Leon... Gaius, one day strangling the patients he once tried to save, cold, pale and no longer Gaius...)
“I’m a liability... useless,” without the magic. “I can’t protect you.”
But Arthur only punches him hard in the shoulder, continuing onwards.
“...Arthur, you should go,” Merlin says quietly, as they begin to hear shifts in the rock. They are getting closer.
“Shut up, Merlin.”
More rocks tumble down. He can see more light up above; smell the rotting flesh entering their stone prison.
“Shut up, Merlin, and don’t mention such nonsense again. Who’s going to carry my sword when I need it? Who’s going to keep watch when I’m sleeping? Who’s going to be my... my...” He stops, tense and cutting off what littler circulation Merlin has in his wrist. “You’re not going to die, Merlin. I forbid it. I absolutely forbid it.”
Hands, there are hands reaching out of the crevice, grasping wildly for the last two living beings in Albion.
Arthur’s face is expressionless. “No, Merlin. I’m not leaving you.”
Groans and whispers, “Flesh, I smell it... I smell the boy-king and the wizard... Flesh, flesh, flesh...”
He thinks that he hears Merlin give a sob. But then his manservant is laughing hollowly, “My life is nothing compared to yours. Please, Arthur, I’m just a servant, no magic, nothing. If you die, I—”
“No, Merlin,” Arthur says. “Your life... is everything to me.”
The rocks fall down, hard and then they are there, wearing the faces of their loved ones, staggering towards them both with fevered hunger.
In one hand, Arthur holds Merlin’s as if his heart (and he isn’t sure whose) will stop beating if he lets go. In the other, he has Excalibur.
“...What did you want to do, on your last day?” Arthur asks softly.
Merlin chokes out a laugh. “Protect you,” he replies without hesitating, there is little point in hiding anything from Arthur anymore. His second answer comes out as a whisper, soft and frail, “...Love you.”
An ache, regret, bleeds into Arthur’s mind, just as the first undead soldier descends upon them.
“...I as well,” he answers shakily and as Merlin gives a small gasp, he adds, “...I’m glad you’re here, Merlin.”
Then he lifts his sword and brings it down on the first undead that leads the hoard.