Moonlight - a brief Saiyuki fic
[Author's note]
I've imagined that Konzen is in the Sanzo body, but that his awareness is "submitted" to Sanzo's, when the monk is awake. When Sanzo is sleeping, Konzen's awareness is free to show up, but the god is just a spirit, because the tie with Sanzo is only spiritual. Sanzo's body can't be used from Konzen spirit.