Draco entertained the insane thought of brokering a marriage deal with Death so just that he could tie Harry to the mortal world. Hermione was utterly convinced that because Persephone's marriage to Hades allowed her to be a part of the Underworld then it could only be assumed that Draco’s marriage to Harry would allow Harry to be a part of the mortal world. It truly was insane, but Draco could see the desperation in Hermione’s eyes. She was far past sanity and she knew it. Even worse, she didn’t seem to care. 