i think they will just focus on Arien's awakening as a heibi descendant since their biological mother isn't human to begin with. Arjen had a large portion of royal blood in him which means he's stronger than Arien and i think it's actually interesting to why the twins had different flows of their blood. I don't think Arjen will be tossed aside as u all say but i just think that the 2nd season will focus more on Arien's awakening as a heibi rather than the imperial princess.
this is actually a wholesome yet a cute plot for a BL.