It is always the same.
Time and time again, Dark allows himself to be seduced by mortality. Upon awakening from slumber, he is doomed to tie himself to the world around him. Doomed to long for such ugly, ordinary things. It infuriates Krad, for cannot Dark see that he—they—are extraordinary? They are infinitely superior, and Krad is determined to show this to his other half.
Humans are fleeting. Humans are the blink of an eye to them. That is why their lives are meaningless. His Satoshi-sama is perfect. Satoshi-sama is flawless…but he is of human flesh and soul. His life means nothing to the vast skies, ephemeral as a butterfly. A butterfly who will grace the earth for the budding blossoms of spring, and be dust when the first leaves fall.
(There is one human he hates more than most, and that is that idiotic Niwa boy. Twice he has spited Krad—once, when he stole Satoshi's heart, and then with the theft of Dark's.)
It is true that mortality is beautiful. This, the angel cannot deny. But immortality…immortality is epic. It borders forever. Humans are slaves to time from their first breath, building cages about themselves with walls made of minutes, of days, of years. But Dark and Krad are special. They can walk through those walls unscathed.
Dark refuses to accept this, though. He does not understand he belongs with Krad. Before being torn apart, they lay in abyss entwined together, as they belonged. Since they first came into existence centuries ago, the thief resisted. They are two halves of one piece of art, and they cannot help but to call for each other. Dark will happily deny this. But time passes, and it has made his heart heavy as he watches people fade to dust and die while he remains eternally the same, immutable to time. And nobody understands Dark the way Krad does. Nobody alive, no human ever cares for more than the one side of Dark they see. They see the confident, handsome thief, and are content to never look deeper. But they are blind to the ages in those purple eyes.
He can see everything in Dark's eyes, and they are growing weary. He will soon crumble, his will weathered by time and loss in the way a cliff is weathered by the waves of the sea. He will join Krad as he was meant to. He has already fallen once. Just once, and then Krad was there to catch him on the way down, holding the thief's shuddering body in his arms as he choked and sobbed in the rainy night. Just once, but it was enough.
(They can fall together.)
Dark is falling fast, plummeting like a stone. Krad can sense him scrabbling at his life lines; at humanity, at all those silly, naïve little things, but in the end he will fail, and fall into abyss with his other half. Their souls fit together perfectly, and their world will be balanced again. He is not quite there yet, though, but it will happen. All it will take is one little push over the edge.
The angel is patient. He can wait.