Prompt: A matter of mechanics

[sirithromeniel]

Prompt: Magic cannot create, only transfer. This is why it must take life from one to give to another. It could take Ygraine's life, her vitality, but not her spirit; for each spirit is - must be - unique. As such it had to find a spirit somewhere else. This is why Arthur is the Once and Future King. He is a genus locum, Albion incarnate. Essentially, on a spiritual level he's not allowed to leave. The details (including discovery, if any) are up to the author.

Characters: Arthur (mention), any to suit author's needs
A/N: I would find canon compliant alternate perspective perfectly acceptable. Mainly just looking for anyone else's take on exploring this idea (comment conversation instead of actual story equally welcome).