Different DxD Retold (I have Permission from the original author)

Issei is dying. He's Sona's fiance even though he doesn't know it. How will we prevent him from dying and what will he do when he finds out he's engaged to Sona? Non perverted Issei. Strong Issei. Smarter Issei. Issei x Sona. Rated M for later on in the story and occasional profanity.