yep he's not lover but foreign servant (slave maybe?)
spoiler.........
he isn't because:
1 he's a "new soul"
2 kaveri didn't reincarnate
he is one of ilya's descendent but not his reincarnation
rejection for N1 Khaol said "his ancestor were different haired foreign slave in the palace" and Khaol did something cruel thing to River's ancestor that's why their family got involved with God of pain. i guess lol
the thing with him being a new soul is that he isn't anyone's reincarnation as he never had a life before this one
River might be the reincarnation of Khaols previous lover Kaveri. Lets see.