Title: Stage of the Dark Souls
Mihael is a devil that lives among humans. Though he shouldn't, he ends up falling in love with a particular human, a man named Adonel Schravant. He is particularly in love with his stunning soul, which Mihael desperately wants for himself. Unfortunately, no matter how hard he tries, Adonel is always being swept away by other humans. Unwilling to share Adonel anymore, Mihael goes to the clergy and tells them that Adonel's family is practicing pagan worship, which leads to their execution. Alone and desperate, Adonel is ripe for the picking, so Mihael makes him an offer he knows Adonel can't refuse: Mihael will tie himself to the Schravant line, granting them all of his powers. In exchange, once the Schravant has fallen in love with Mihael and willingly given his soul, Mihael will take it, and they will be bound for eternity.
So Mihael lives in Adonel's shadow, helping rebuild the fallen Schravant name. All the while, Adonel has a child, despite Mihael's hate over it, and grows to a ripe old age. Finally, at the end of Adonel's life, Mihael broaches the subject of Adonel handing over his soul. Only then does Adonel reveal that he never loved Mihael and would not give up his soul, meaning Mihael would remain tied to the Schravant bloodline until he can convince another descendent to fall in love with him and willingly give their soul to him. Mihael is devastated but far from willing to give up.
Three hundred years later, after the death of the head of the Schravant conglomerate, Mihael finds his two sons: the firstborn, Evan, and the second, Victor. Mihael has been watching over the family all this time, biding his time and waiting for the ideal soul. Finally, after all this time, Mihael has found it. Two of them, in fact, and he isn't willing to give either of them up. One way or another, he will make them fall for him and then take their souls, but not until he destroys them from the inside out.