User blog comment:B214/Volume 22 spoilers/@comment-30048084-20161031183100/@comment-10330822-20161113015141

Also, it would be kind of interesting if it was a girl whose parents weren't completely sold on Issei like the other girls parents and surrogate parents are. Something that wouldn't be solved by the end of the volum like Akeno. That I feel would add a new dynamic. Since Issei is the King, "he" would be the one turning them into a devil, meaning he may make a parent resentful in the process, and he may need multiple volumes to prove it was a right decision.

Or what's more, maybe a girl who comes from an abusive household, and Issei saves her in a more literal sense.