He thought that might have been Arthur's worry, but his responses kept telling him different things. Merlin thought he might want him around, maybe feared loosing him, then he went and said things like that.
"It's our destiny." Merlin smiled and shrugged. "I have to make sure you live long enough to be the great king I know you will be." The idea that it was destiny sounded ridiculous saying it out loud, but wasn't that what he kept being told?
"Royal prat or not -- you're my friend." He said it with the hope that maybe Arthur would say they were friends.