Responses
someone answered this question on the comment above by accident, they basically said that it's based on their magic more than anything. Emperor has a green magic= green eyes, first prince black magic= black yes.... etc
Ohhh, thanks for informing me tho (=・ω・=)
Tho the twins look nothing like Rurahel, and much more looks like the emperor, im kinda wondering how they got reddish orange eyes(?) since the emperor had green, and rurahel had violet magneta eyes.