User blog comment:B214/Volume 23 discussion blog/@comment-31137559-20170423170210/@comment-31137559-20170423213613

As a Longinus possessor, Issei is Rias' most unique servant that regular devils have never gotten.

As a Longinus itself, Regulus is Sairaorg's most unique servant. Again a servant that no other devil has gotten.

As a Grim Reaper, Bennia is Sona's most unique servant. And unless there are drastic changes, there won't be another devil getting a Grim Reaper in their peerage due to them hating devils. Not to mention that Bennia would fit more in Sona's peerage. Bennia joining Issei at this point would just be an asspull. Is Akeno going to become Issei's queen because of her feelings for him?