
Well Medea wants power for herself ever since chapter one. She may be the most talented and more intelligent but in the end the heir will be the eldest son. Same with psyche, no matter what she did in the contest, she was the best but the chosen bride to be the queen is not her. Her lust for power is befitting for being Solon.
Power to protect herself and her love ones, and so no one can look down on her, neither the king or his father that shackle her.
But Dekis is different, how can a good sane person born in that house with that kind of father and environment, where did he pick that good nature of his. He just want to live Normal life, he does not wish anything because all the attention are already his for being eldest, heir. He get what he doesn't wish for.
Sigh it's sad to see them torn apart because dekis may see himself as a obstacles now to get what Medi want. This maybe Medi's plan or not but in the end their relationship made a inevitable crack that separate them.

Heirs in olden times were often decided by gender. Here in the most recent chapter it’s shown that Demi’s received all of the praise and recognition while Medi stood on the sidelines. While it’s not directly announced it’s made very obvious that expectations are high on Dekis to perform perfectly as a Solon. I’m not sure why Medi was smirking, but it might have to do with the father being furious with Dekis, which in turn would make it easier for Medi to take the position of heir.
Soft ♡