Incubi and succubi both exist

When Lucifer was cast out of heaven he kidnapped and corrupted the first human Lilith to become the first demon and used her to birth the 72 pillars of the devils. Lilith being the first demon what made her incredibly powerful unfortunately due to the fact that she was always forcibly pregnant she could never truly exercise her power before her **** however before a few years before she died she was pregnant with two of asmodeus' children but what she did was instead of give birth to Devils she altered them creating the first Incubus and succubus unlike devils these two creatures game power through sex the more they have the more powerful they are. Because she was going to use these as part of a **** knowing she would most likely die from constantly giving birth she sent them to the human world so that they wouldn't be hunted down by Lucifer and his followers. Fast forward a few thousand years of the future well the incubi or succubi never reached a huge population one of the characteristics that they possessed was upon birth they took mainly after the race that they had sex with such there incubi and succubi Heritage was dormant until they had sex for the first time and with time could either the Bloodlines of both into something beneficial or they could completely in addition they can also even gain racial traits by sleeping with other races. Well they did their best to hide most incubi were usually killed if found some were taken and and kept as pets for powerful females and succubi were usually turned into sex slaves for various pantheons and factions no succubi or Incubus had ever reached Beyond low God level.

( okay so I left it open for you guys to either create your character or use a character from DxD such as Issei or Aika for example you can use others note like what I stated their power comes from the more sex they have but also applies to the strength of the person they sleep with so it's a combination of quantity and quality when they have enough magic that comes from sex or lust energy they can do anything such as gender bending body modifications( this applies to themselves as well) hell even Reviving The Dead if they feel like it (no zombies) because the other races found out about it it is this very reason why no succubus or Incubus ever reach Beyond low God level because out of all Races they have the most potential with little to no weaknesses)