At one point or another, Cyprus knew everything there was to know about the Sailor Zodiacs, the Black Stars, and the Zodiac wars. But, soon after dropping Tia's ring for her to find, he ran head-long into a low branch and forgot everything but his mission. Sad, isn't it?
Cyprus's original job was to protect Sailor Gemini in particular, although he can't seam to remember exactly what is so important about it. He's very dignified and royal, but occasional acts little strange, probably caused by the bash on the head. He is devoted to his job and blames himself when anything goes wrong.
Secretly, though, he is in love with Selene/Sailor Gemini and would lay his life on the line to keep her in particular safe. Selene, however, has no idea he feels this way about her and just considers him a dear friend.
Cyprus also has a human form, as seen above. He's about the same age as the Dark Zodiacs, making him about 21. He only does this transformation in emergencies, or when it is necessary to defend his students. In his bird form, he talks using telekinesis and often first contacts the Zodiacs through his own speacial dreams.