User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-73.57.25.92-20171205192958

This is what @bennia lover said on forum.animesuki.com about the picture with vali being hugged by lavina. "Dark Past Notes

Three "magical" books written by Vali four years ago, "The Book of the Mind", "The Book of Techniques", "The Book of Art" and the cover with the name "Vali Lucifer" written in English. The Book of the Mind is a collection of chuunibyou filled content; basically what the book is about is this:

"中二病" and this represents the second grade of junior high school. It's a word to represent people who will never be a grown-up and stay fourteen years old forever, in a "negative" meaning, not a good way.

People (mainly teenagers) who are addicted to Manga or Anime tend to imagine they are special like a Manga/Anime character. So they act like special characters. Most of them notice their attitude is creepy when they grow up, but some people keep pretending. It means they still can't recover from chuunibyou. When they recover from it they call their shameful time "黒歴史"(dark past).

The Book of Techniques is also full of chuunibyou content; made up techniques and such.

The Book of Art is written with strange names, magic and various postings when it is invoked with illustrations, and also with things that seems to be spells.

Vali had searched for these books and he found the Book of Techniques but the other two are kept safely by Lavinia. Because it seems that the spirit of Vali is going to be unpleasant if he is shown the contents of the Book of Techniques, it is supposed to be unviewable except for his fateful rival Issei and the "SLASHDOG" team. Although Vali had negotiated with Lavinia and begged for the original two books she has, unlucky for him, she had duplicated them with her magic. Poor Vali

This info I have no doubt in my mind was revealed in the SLASHDOG X DxD SS and it would explain why Vali looks so embarrassed when he is being cuddled by Lavinia in this illustration https://vignette.wikia.nocookie.net/...20171117173155, because that's when he found out about the duplicates. Speaking of SS, I want to see the illustration of the Elmenhilde SS that came with V24. Anyway, Vali used to be a major chuunibyou and I have no doubt he got that from Azazel"