User blog comment:B214/Question & Answers 5/@comment-50.108.164.34-20151204041232/@comment-213.120.234.122-20151204113752

I've heard this being asked a lot, and even though I agree it would be kinda cool it is simply impossible. Reynare was completely destroyed by Rias, there was nothing left of her. Sure there were some feathers left according to the anime but I'm sure they were disposed of too. If there's nothing left of her I'm sure it's impossible to bring her back. And there's no way she would serve Issei, she would most likely want revenge.