in a nutshell (слэш)

“Merlin, you must prepare yourself,” Gaius says gently, and Merlin thinks of Arthur’s fingers in his hair, the warm curve of his smile, his mouth, his hands. How is he supposed to prepare for the end of the world? “No news is seldom good news in cases like this.”
 
When Arthur is kidnapped on a routine visit to Mercia, it's up to Merlin to find a way to get him back alive.
Prequel to a king of infinite space, but can be read as a stand-alone.