Destiny and Dragons
It hits Merlin as fast as a bandit's sword in a surprise attack - he is perfect. Every thing about him is perfect, including how his teeth are a bit crooked and how his addam's apple is too high. His arrogant voice gives him shivers, and the challenge is something he can never let pass.
His whole being was vibrating with the emotions this man woke in him, all the things he hates used as a way of luring him into getting closer. It is inevitable - his heart is beating too fast, his eyes are darting, drinking him in, and even loosing wouldn't be too bad if it weren't for the last sentence.
"I am his son. Arthur."
It can never be, and it hurts more than the twisted arm. The prince wasn't anywhere near the kind of person he could be close to.
And as the great dragon talks to him about destiny, he rages against it, because he can not do it, he can not make Arthur less perfect for him, he can not spend his life grooming him to be a better man, he can't deal with the heartache that it will be seeing him all the time and knowing it will never be.
He can't avoid the next confrontation, even knowing that he should, for he is still young enough to try to fight against destines - he just wants to feel swept away one more time before accepting it will never be more. They will have to walk apart and thread different paths from the one that would lead them into each other's arms.
When the King names him Arthur's manservant, he knows he is doomed.
He can not fight destines, dragons or the love that will guide his life.