War was taken out on earth between Hell and Heaven. Hell wanted a stronger, larger army and the pure to suffer. Heaven wanted to save the pure from the claws of the Devils whenever the souls of the pure were on their path to heaven. The sinners were immediately sent to hell.
Alfred was pure. He was killed by protecting his younger brother, and he was only nineteen.
An arch angel was sent to retrieve his soul, one of the purest souls to be seen in years. That had meant that whichever way he was taken, Alfred would be powerful. The angel lost to several demons who sought after Alfred's soul, and Alfred was taken to hell, where he became the Demon King, or King of Hell.
Many decades later, Arthur, an angel, is captured and dragged down to hell. The King of Hell takes a great liking to said Angel, who strives to return home to heaven.
I do not own Hetalia or the characters or the pictures used. I do, however, own the plot line and story.
Thank you for reading!