Just as the original games bosses are based of the Seven Deadly Sins, The Seven of the second game also have their own theme which by now everyone can agree on: Fairy Tales (I mean that's what the grimoires are called in Japan so...). I've made this so we can figure out who fits with what fairy tale. Here is what I think:
Tenjian = Snow White (His powers are a literal interpretation of the name, the fact that he was poisoned, and also that he is seen with an apple.)
Teseo = Sleeping Beauty (His association with pins, spinning wheels and thorns.)
Ghauri = Cinderella (His love of dancing and his crystal heels, plus, GV mentions the clock striking twelve when fighting him.)
Desna = Rapunzel (Her hair septima speaks for itself. Not to mention she's fought in a large tower.)
Milas = The Little Mermaid (His aquatic based powers)
Asroc = Pinocchio (His puppeteer septima. I've also seen people suggest Hansel and Gretal)
Gibril = ???
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"Mysterious Girl" = Alice in Wonderland (more specifically, Through The Looking Glass)