Arthur blinked. "I am not a baby!" he protested. He was pouting slightly, though if he was honest this felt much more comfortable. Trading barbs with Merlin, having him treat him with gross disrespect... it was reassuringly familiar, in a way.
"Well. Maybe you have, but at least I'm not a sorcerer who walked into Camelot and took a job in my father's court. I'm frankly surprised you've kept it a secret this long."