Serendipity

Yoongi lived the life he knew. At least the life a demon could know. But what happens when he meets angel Jimin, in a world where there is fight between angels and demons?

Explanation:
-Normally demons mate with demons and angels with angels
-Younger ones are the bottoms in most relationships
-Every demon/angel lives in a 'family' and each family has it's 'master', who you shouldn't fight with