The Riveran Brothers were born into nobility within the kingdom of Soui and wear their status on their (semi-present) sleeves, rarely seen without particularly fancy-looking clothes. Though being physically identical and having roughly the same voice, it's become very easy to tell the two apart between how they carry themselves.
Frostolas is the more "traditional" of the two, and has become popular as both a famed swordsman and the expected heir to the family's fortune due to his immense strength and can-do attitude. He always seems to be trying to make the most of a bad situation with a responsible mindset and a smile on his face. Of the two's mutual origins as Water adepts, he takes a liking to cryokinesis when he deigns to use his magic, forming ice across the ground to disorient foes, and around his hands to maintain a solid grip on his sword and give the blade a colder bite. However, even without using his magic, his hands always seem to tremble when he's asked something.
Azulos, by comparison, is no less joyous, but is far less energetic at a glance, eyes always half-lidded and speaking in a slow, even tone that's easy to confuse with a sense of depression were it not for the subtle smile and genuinely motivational advice he's capable of granting. He's known to give a coy smile when he knows eyes are on him, and it's hard for eyes to stay off him, given he's rarely seen without his black and blue striped gloves, one of a number of silk dresses, or his dazzling gold-plated cuffs. Lacking his brother's physical might, he instead finds his aptitude in magic and speed, being quick on his feet and using his hydrokinesis to create visual spectacles when the mood suits him.
But the one thing that they share unambiguously, is their love for the kingdom's Princess - Fiume Iizali - Only time and their actions would tell if anything can come of it,.