i do love the early dynamics of merlin and arthur. merlin doesn't want any of it, arthur doesn't know any of it quite yet, and they're already in this push and pull of duty and choice. it's very interesting to see merlin learn about arthur and his sense of duty, really it's one of the first genuine parts of arthur he sees. and from the other side you have arthur finding about merlin's intense need to do what's right (or, in other words, what's necessary). this is not say that one has this trait, and the other does not, the two of them do posses both traits to a certain degree, but there's a contrast of situations, as well overall being. that's what creates the push and the pull. especially when duty and choice can be taken as something that goes hand in hand, as well as something that's opposite from the other.
merlin getting the lesson of ‘your word does not matter, not against people of higher status’ so early on only to 1. pretty much never listen to that advice 2. prove everyone wrong because he WILL get his way