User blog comment:B214/Volume 22 spoilers/@comment-30319856-20161025113305/@comment-30048084-20161026190556

I doubt it even though earlier I actually said the same thing. B214 mentioned the possibility that she could be Ajuka's queen, which if you look at the fact she went with Ajuka when he kept Shiva company is possible or for some reason the debt she owes him is enormous.

Let's say she is Ise's queen the fact that she is a devil could be Tiamat using a forbidden technique to make her aura/magic powers appear to be that of a devil and restrain the amount of power she is releasing to explain her only being a high-class devil instead of a maou-class being.

The reason she could possibly have instead of judging Rating Games started participating in them instead is because I highly doubt they will let her go on a rampage ever again considering the current situation so she is using the rating games as an alternative.

The reason she didn't make a peerage of her own is because a king typically doesn't do much but stand around and give orders until the end of the game and only go out then if it is necessary. Ise, Sairaorg, Vali and Cao Cao(if he is honestly bored) could be exceptions to this rule because of well their respective personalities. If she is a king she wouldn't be able to fight much.

As previously stated she hates Ddraig that doesn't mean Ise would also be the target of her hatred automatically. She most likely went and offered her services to Ise on a trial basis to see if Ise is in her opinion worthy of being her king and she was curious. Not going after Vali could be because Vali is a battle maniac. She could also believe that she would only be willing to be subservient to a Dragon(Dragons Pride) that is stronger than her and in DxD G mode Ise is on par with a Heavenly Dragon and now possess a power that can kill a god.

Considering Ise has Ravel at his side all the time that means as a Queen she doesn't necessarily have to always be with him which seems to be a norm in devil society though there are some exceptions.

Those are possible reasons for her to become Ise's queen though this is pure conjecture. I would love it to be Tiamat because this gives Ise an instant (piece) that can help him fulfil Sirzechs request that he watches over the devils in his place and maybe become a Maou in the future(volume 21, got this from Baka Tsuki translation)