Just a random thing that just popped into my head, like a minute ago.
I don't know why but I would say Lance
i guess it would be artha. lance is after all 10 and artha is 16.
artha is more mature age-wise, i dunno about intelectualy, though!
beau is smarter though. he's the brains of the duo. -_-
i think that lance is more mature to a certain extent but in some cases artha is way more mature then lance but i think that lance is more intellegant on occausion as well because artha tends to think with his ego where lance tends to think like mortis ( connor) and remebers wat he is trying to teach them