PIECE OF HEAVEN
Why I chose this title?
Because Teito and Ouka are the owner of Mikhael and Raphael's Eye, so they have a God into their body!
Also, Mikhael and Raphael could appear when they lose control, giving them all their power.
"Piece of Heaven" is a part of Paradise, the place where Gods live. Teito and Ouka take this place in this word, and it's very romantic to me! I'll never choose another title for them.