User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-1359322-20141119194655/@comment-24552694-20141120160038

See, this is evidence that Gasper and Valerie have a strong sibling bond, just like Kuroka and Koneko. We have to wait and see some more interactions between Gasper, Valerie and Issei before any solid pairing can be assumed. Tough the author has been hinting that that Issei may be getting his pieces sooner than Kiba and Akeno and that he might get a Longinus user on his team. With how Issei has took down Eculid in Volume 17 and how he batlled Rizvem in Volume 18. Also, ot makes sense for Issei then Kiba or Akeno then the fi al one to get their EP's at different times, puts less strain on the Author to cone up with Peerage members for them all at once