User blog comment:B214/Volume 17 spoilers./@comment-117.193.172.96-20140220172147/@comment-82.48.169.148-20140220190209

My theory: Tiamat che shape her bodi like Crom Cruach in a human body. Tiamat was in love with Ddraig but he didn't (Ddraig said to Ise that Tiamat hate him and he doesn't know the reason). Tiamat could fall in love with Issei (that is the wielder of Ddraig).