
Bc in the following chaps the twins will get their powers and the brother will want to some of his power to the sis but he will accidentally give all of em and then he will be the most powerfullest smth which I forgot and the sis will have the most power in the whole empire and then she will go wif the Guardian and they will make the bro a side character and I thought this was a twins thing but in the end it is like this so I am disappointed

no argen does not become a "side character" the whole story is about them. the second half of the plot just focuses a bit more on the hiebi's and arien. which is fair.
we already learned argen has a stronger connection to their guardian jason thanks to his stronger noble blood then her. so I guess they tried to balance it by having jason connect better with arien in a different way.
I dont see any issue with arien getting strong magic tbh. thats just a matter of opinion, not a flaw in the plot. argen goes on to become a great knight, which is cool. arien will probably never learn how to use a sword and even if she did she wouldn't be as good as her brother.
Wtf (︶︿︶)=凸