Why does he want to spread her picture
Definitely not! You expect a yandere to share his most precious person with another individual? Rezef only promised that Cayena could marry whomever she wanted. He did not say that Cayena would be allowed to leave Rezef to live a married life with her husband. His angelic older sister gotta stay with him forever~
So yeah, he's spreading her face everywhere so Cayena can't hide her identity and flee the country (which is why he's prioritizing ports, since she's more likely to escape by sea).
Why are they obsessed with hair colour