you, me, and lust makes three
Desire makes no secret of the fact that it plays favourites. Ohtori Akio is one of them. He leaves a trail through the world like a body cleaving through sea-foam; he cultivates the walled garden of his school and then plucks the roses.
But to Desire, the sweetest thing of all is everything that Ohtori Akio feels for his sister. Ohtori Akio could have everything and anything that he wanted, and he does -- except for the little matter of the better part of his nature, and really that isn't Desire's thing at all, that's Dream's business, or perhaps Death's, or maybe even Despair's. It doesn't bother Desire; Dios never had any dreams that interested him, after all.
Ohtori Akio wants his sister. He wants her to love him and only him. He wants to punish her for saving him. He wants her to take the world's punishment. He wants to save her from it. Ohtori Akio has all the time that there is in stories to want this, to need this, to desire this, to learn that his sister's skin is as soft as rose petals, that her hair smells of the evening dew, that she will cry for him but never for herself. He's had all that time to grow to hate her and to want her.
This doesn't stop Ohtori Akio from wanting other people as well. Their innocence is a temporary balm for his own knowledge; their steps into experience make him feel a little less damned, for just a moment. But they're not his sister. So he punishes them for that, as well.
Ohtori Anthy wants her brother Dios. She loves her brother Dios. She will do anything for her brother Dios. She can't live without her brother Dios. She deliberately locked away what Dios was in order to save him. Each man kills the thing he loves. It's gorgeous. It doesn't have quite the same flavour as what Ohtori Akio has for her; it lacks a certain tang, but there's a note of self-blame and self-despite and desire for punishment that Desire finds quite piquant.
Ohtori Anthy doesn't want other people for their sake; she wants them to prove that she is worthless and to treat her as she deserves. And when they fall, it's no more than they deserve. She doesn't dream of anyone except her brother; she doesn't have anyone except her brother. She punishes herself, and it involves so many other people, so prettily, that Desire reaches inside her to taste the trembling of her satisfaction.
Desire is in both of them. It is in Ohtori Akio's body as Akio's hands tangle themselves in his sister's hair; it is in Ohtori Anthy's body as Anthy curves herself against her brother and feels his heartbeat. It is in Akio's eyes as he looks down from his tower at his sister below; it is in Anthy's eyes as she waters her roses and sees her brother through a veil of rainbows and tears. It is in Akio's shadow as it falls across her body, and it is in Anthy's silence as she bows her head; it is in their mouths as they kiss.
It's true what they say. Corruptio optimi pessima est: the corruption of the best is by far the sweetest.