User blog comment:B214/Volume 23 discussion blog/@comment-31137559-20170410191626/@comment-31137559-20170412123228

Roygun is temporarily banned from the Rating Games. She loves the Rating Games so much that she became Issei's retainer just so she could compete in the Azazel Cup. She can be his team member without being one of his servants in this tournament. It's not like she's banned from competing in the professional Rating Games forever. And her sentence is far less harsher because she helped taking down those who used the king piece and were exposed. It's going to be a long while before Issei starts competing professionally in the Rating Games and Roygun is just banned temporarily from the Rating Games. She just wants to become his team member for the Azazel Cup. She just has to work her way up without a king piece in the Rating Games.

Those three points you made doesn't equate to Roygun joining his peerage. She likes him and is already a devil so she can just stick by him. Who's going to stop her by doing so? She can also raise her reputation by just being associated with him. The Vali Team was pardoned for their crimes because of their association with Issei. She already provides that insider info since she's his retainer.

She has already put herself under Issei. She doesn't need to become his servant to do so. Remember how Vali was talking about having servants that aren't in your peerage, like retainers? Now she is still a king and will be able to participate in the Rating Games again, but she can't compete in this tournament. Which is why she put herself and her peerage at his disposal.

Now my personal feelings about having any more pureblood devils is very biased. And I see no point in her wanting to become his servant if she can just become his retainer. And she's a king already unlike Ravel and Grayfia who decided they would rather be servants than get their own set of evil pieces. And who knows? That might cause problems like B214 said. What happens when Bedeze Abbadon comes and asks to join Rias' peerage? Some other kings would probably use the influence of an up-and-coming devil to improve their standing and would just break the evil pieces system which was mainly for the purpose of making other species into devils.