The paring is Hadrian X Nuala.
Also, Hadrian may have tried to give up his immortality, but Death has taken a liking to Hadrian,so he won't give up on his companion so easily. So Hadrian is a pseudo immortal like the LOTR elves, he has superhuman regenerative and longevity.
Hadrian after the War between Human and magical beings would create a dimension of his own like Tao Lo from MCU with Death's help.