The Letter that came Late

Fai and Kurogane had met one another long before the meeting at Yuko' s home. Their first meeting resulting in something they did not expect.
You see Fai's people, while having the usual magic, also have an odd ability. Each gender can carry children; Fai had forgotten that in his long exile.
The king Fai served knew of his own growing madness and in order to protect Fai's child he sent it away to another world into the care of a guardian.
Yuko had not been able to give Fai the letter the king wrote to him but Watanuki did.
Now both bearer and sire journey to get their child back, with help from their young friend and bouncing bun-bun of course.