Fantasy-read 2005-2008, gods from different mythologies are teamed up together in twos and have to survive on a different world alone

[Brittany]

Fantasy- read 2005-2008; two gods from different mythologies are put together on a deserted plane (like a nether realm?) and they have to survive. One of the gods is male, he is a Native American god of children. Cannot remember is name. The other is a woman, from what I remember she is a bit unpleasant? They build temporary shelters by a lake, I believe there’s lava at some point?

can’t remember much about it except that the characters are all alone in this place trying to survive- maybe they’ve been placed there as a test? I believe they also end up falling in love? Sorry it’s so sad that’s all I remember.