“What?” Sire. There’s something nagging him about that word. Never mind that it’s a title for royalty, but when Merlin says it, there’s a ring to it that hints at something deeper. Ancient. “Why are you calling me that?”
A snort. “For years and lifetimes you tell me to give you the due respect you deserve, and now you’re opposed to me calling you that? Typical.”
Then Merlin’s nuzzling his cheek, lips just brushing his skin, and now Arthur’s heart is beating too fast because of something else entirely.