The ruler ashikabi

For this scenario you can create your own character or choose a character within the series as the ruler ashikabi has the ability to Wing any Sekirei even if they belong to somebody else and make them theirs supposedly it even has the ability to turn other people into sekirei

For those who don't know they don't really explain how the sekirei came to be all I know is there supposedly aliens .the ruler ashikabi came about between the union of sekirei and humans but that's just how ashikabi at least according to the manga but as for the ruler trait to apply think it has a rare Gene appearing because they also explain the regional ashikabi has the ability to temporarily deactivate the ability of other sekirei this ability is possessed by Seo but the ruler ability goes quite a bit step further with by forcing it their own Bond upon them superseding the original ashikabi not to mention that the ruler can turning people into sekireis the ruler awakens the dormant sekirei genes in the person's body or can insert these genes into a person

So for this one you can pretty much do whatever you want if you want to have futa go ahead or NTR note that not all of the 108 sekirei make an appearance in the book or even the manga so there's a lot of room where you can just put characters from other things into here as a sekirei just give them a power similar to what they would have in their Source material be warned there are male Sekirei as well as females there is also one that can switch gender so gender you can do whatever you want with it. With the ability to take other people's sekirei is mainly to deal with the problem ashikabi