Unstoppable (Seven Deadly Sins)

This is my first novel so sorry if there is anything bad about the story. As Meliodas and the sins are out patrolling the area a couple miles away from Liones, they meet someone named Asmodeus who threatens Meliodas that if he ever goes on a slaughter again, He will kill Meliodas. Just who is Asmodeus and why does he have it out for Meliodas? A Seven Deadly Sins Fanfiction