Demonic or Angelic

in the deep core of earth, there lives 2 species, the land was divided in two parts, one where Angels live and one where demons

in the crust of earth when the humans born, developed, The angels and demons came across to live with them, hiding with them, not knowing eachother

but once a year they have to leave for 30 days, to their own land , to do a festival, war, and decide who will rule the land for that year.....
what will happen if demons and angels fall in love......