Work Text:
Over and over again, Merlin gives his life, trades it for Arthur's, and Arthur is forced to live without him. It never lasts more than twenty-three years for them, twenty-three years of existing in the same flow of time, and it's even less because Merlin never meets Arthur before seventeen. One lifetime, they only knew each other for a second before Merlin pushed the blond out of the way of a speeding truck.
When Merlin goes, the memories come flowing out and into Arthur, awakening something old and precious, like Merlin was its vessel, and Arthur has to make sure he lives his life how he's supposed to. No cutting it short, no wasting Merlin's efforts, or there will be no next time. He has to live lifetimes that stretch out too long without looking in the sky first thing in the morning, without running fingers through soft earthy locks. Every time is like the first, but worse, and Arthur never gets used to the spaces Merlin leaves behind.
Merlin is already so practiced in this twisted form of art. Giving his life for Arthur becomes nothing and means everything.
“It's my destiny,” he answers every time the next Guinevere or the next Morgana remembers. “It's my destiny.”
He sees the longing looks from the corner of his eye, and once upon a time they tugged at his heartstrings.
He'd never had a choice; there was never any alternative, not when it came to Arthur.