He cared for Teito very much, having raised him and being his primary father figure. He is actually the King's younger brother, making him Teito's blood uncle. Although there are many differences between him and Frau, Teito is still reminded of Kreuz a lot when Frau is being serious.
Fia Kreuz is also another of the 07-Ghosts, Vertrag.
Seiyuu: Kiuchi Hidenobu